diff --git a/routes/api/baseline/update.ts b/routes/api/baseline/update.ts
index 887ba97a..f2029987 100644
--- a/routes/api/baseline/update.ts
+++ b/routes/api/baseline/update.ts
@@ -6,7 +6,7 @@ import { BackgroundTaskQueue } from "../../../utils/background-task-queue.js";
 import { store } from "./lib/store-init.js";
 
 const workerFile = path.join(import.meta.dirname, "update.worker.js");
-const taskQueue = new BackgroundTaskQueue<typeof import("./update.worker")>(
+const taskQueue = new BackgroundTaskQueue<typeof import("./update.worker.ts")>(
   workerFile,
   "baseline_update",
 );
diff --git a/routes/xref/index.ts b/routes/xref/index.ts
index 9bc774a2..e605f35e 100644
--- a/routes/xref/index.ts
+++ b/routes/xref/index.ts
@@ -12,6 +12,7 @@ import searchRouteGet from "./search.get.js";
 import searchRoutePost from "./search.post.js";
 import headingsRoutePost from "./headings.post.js";
 import metaRoute from "./meta.js";
+import termsRoute from "./terms.get.js";
 import updateRoute from "./update.js";
 import { search, Options, Query } from "./lib/search.js";
 
@@ -26,6 +27,7 @@ xref
   .options("/search", cors({ methods: ["POST", "GET"], maxAge: ms("1day") }))
   .get("/search", cors(), searchRouteGet)
   .post("/search", express.json({ limit: "2mb" }), cors(), searchRoutePost);
+xref.get("/meta/terms/search", cors(), termsRoute);
 xref.get("/meta{/:field}", cors(), metaRoute);
 xref
   .options("/search/headings", cors({ methods: ["POST"], maxAge: ms("1day") }))
diff --git a/routes/xref/terms.get.ts b/routes/xref/terms.get.ts
new file mode 100644
index 00000000..96859aa3
--- /dev/null
+++ b/routes/xref/terms.get.ts
@@ -0,0 +1,79 @@
+import { Request, Response } from "express";
+
+import { seconds } from "../../utils/misc.js";
+import { store } from "./lib/store-init.js";
+
+interface TermEntry {
+  lower: string;
+  original: string;
+}
+
+let termsIndex: TermEntry[] = [];
+let termsVersion = -1;
+
+function getTermsIndex(): TermEntry[] {
+  if (termsVersion < store.version) {
+    const keys = Object.keys(store.byTerm).filter(k => k !== "");
+    termsIndex = keys
+      .map(k => ({ lower: k.toLowerCase(), original: k }))
+      .sort((a, b) => (a.lower < b.lower ? -1 : a.lower > b.lower ? 1 : 0));
+    termsVersion = store.version;
+  }
+  return termsIndex;
+}
+
+function bisectLeft(arr: TermEntry[], target: string): number {
+  let lo = 0;
+  let hi = arr.length;
+  while (lo < hi) {
+    const mid = (lo + hi) >>> 1;
+    if (arr[mid].lower < target) lo = mid + 1;
+    else hi = mid;
+  }
+  return lo;
+}
+
+function searchTerms(query: string, limit: number): string[] {
+  const index = getTermsIndex();
+  const q = query.toLowerCase();
+  const results: string[] = [];
+  const seen = new Set<string>();
+
+  const start = bisectLeft(index, q);
+  for (let i = start; i < index.length && results.length < limit; i++) {
+    if (!index[i].lower.startsWith(q)) break;
+    seen.add(index[i].lower);
+    results.push(index[i].original);
+  }
+
+  if (results.length < limit) {
+    for (let i = 0; i < index.length && results.length < limit; i++) {
+      if (seen.has(index[i].lower)) continue;
+      if (index[i].lower.includes(q)) {
+        results.push(index[i].original);
+      }
+    }
+  }
+
+  return results;
+}
+
+interface QueryParams {
+  q?: string | string[];
+  limit?: string;
+}
+type IRequest = Request<never, any, never, QueryParams>;
+
+export default function route(req: IRequest, res: Response) {
+  const q = Array.isArray(req.query.q) ? req.query.q[0] : req.query.q;
+  if (!q || q.length < 2) {
+    res.status(400).json({ error: "query must be at least 2 characters" });
+    return;
+  }
+
+  const limit = Math.min(Math.max(parseInt(req.query.limit || "15", 10) || 15, 1), 50);
+  const results = searchTerms(q, limit);
+
+  res.set("Cache-Control", `max-age=${seconds("24h")}`);
+  res.json(results);
+}
diff --git a/static/xref/script.js b/static/xref/script.js
index df8ee2d2..2acee928 100644
--- a/static/xref/script.js
+++ b/static/xref/script.js
@@ -235,9 +235,9 @@ async function ready() {
   };
 
   const metaURL = new URL(
-    `${form.action}/meta?fields=types,specs,terms,version`,
+    `${form.action}/meta?fields=types,specs,version`,
   ).href;
-  const { specs, types, terms, version } = await fetch(metaURL).then(res =>
+  const { specs, types, version } = await fetch(metaURL).then(res =>
     res.json(),
   );
 
@@ -260,13 +260,16 @@ async function ready() {
   const allTypes = [].concat(...Object.values(types)).sort();
   updateInput(form.types, allTypes);
 
-  const fuse = new Fuse(terms);
+  const termsBaseURL = new URL(`${form.action}/meta/terms/search`, location.href).href;
   autocomplete({
     input: form.term,
+    debounceWaitMs: 150,
     fetch(text, update) {
-      const searchResults = fuse.search(text).slice(0, 15);
-      const suggestions = searchResults.map(r => r.item);
-      update(suggestions);
+      if (text.length < 2) return update([]);
+      fetch(`${termsBaseURL}?q=${encodeURIComponent(text)}&limit=15`)
+        .then(r => r.ok ? r.json() : [])
+        .then(update)
+        .catch(() => update([]));
     },
     onSelect(suggestion) {
       this.input.value = suggestion;
@@ -330,7 +333,6 @@ async function ready() {
       http: new Set(types.http),
     },
     specs,
-    terms,
   };
 }
 
diff --git a/tests/routes/xref/terms.test.js b/tests/routes/xref/terms.test.js
new file mode 100644
index 00000000..4e192411
--- /dev/null
+++ b/tests/routes/xref/terms.test.js
@@ -0,0 +1,169 @@
+import { mkdtemp, writeFile, mkdir, rm } from "fs/promises";
+import path from "path";
+import { tmpdir } from "os";
+
+let tmpDir;
+let route;
+let origDataDir;
+
+const FIXTURE_XREF = {
+  EventTarget: [{ type: "interface", spec: "dom", uri: "#eventtarget" }],
+  "event target": [{ type: "dfn", spec: "dom", uri: "#concept-event-target" }],
+  event: [{ type: "dfn", spec: "dom", uri: "#concept-event" }],
+  "event handler": [{ type: "dfn", spec: "html", uri: "#event-handler" }],
+  "event loop": [{ type: "dfn", spec: "html", uri: "#event-loop" }],
+  element: [{ type: "dfn", spec: "dom", uri: "#concept-element" }],
+  "foreignObject": [{ type: "element", spec: "svg", uri: "#foreignObject" }],
+  fetch: [{ type: "dfn", spec: "fetch", uri: "#concept-fetch" }],
+  "fire an event": [{ type: "dfn", spec: "dom", uri: "#concept-event-fire" }],
+  "live event": [{ type: "dfn", spec: "html", uri: "#concept-live-event" }],
+  URL: [{ type: "interface", spec: "url", uri: "#url" }],
+  "url": [{ type: "dfn", spec: "url", uri: "#concept-url" }],
+  AbortController: [{ type: "interface", spec: "dom", uri: "#abortcontroller" }],
+  AbortSignal: [{ type: "interface", spec: "dom", uri: "#abortsignal" }],
+  "abort signal": [{ type: "dfn", spec: "dom", uri: "#concept-abort-signal" }],
+  Node: [{ type: "interface", spec: "dom", uri: "#node" }],
+  navigator: [{ type: "attribute", spec: "html", uri: "#navigator" }],
+};
+
+beforeAll(async () => {
+  tmpDir = await mkdtemp(path.join(tmpdir(), "xref-terms-test-"));
+  const xrefDir = path.join(tmpDir, "xref");
+  await mkdir(xrefDir, { recursive: true });
+  await writeFile(path.join(xrefDir, "xref.json"), JSON.stringify(FIXTURE_XREF));
+  await writeFile(path.join(xrefDir, "specs.json"), "{}");
+  await writeFile(path.join(xrefDir, "specmap.json"), '{"current":{},"snapshot":{}}');
+  await writeFile(path.join(xrefDir, "headings.json"), "{}");
+
+  origDataDir = process.env.DATA_DIR;
+  process.env.DATA_DIR = tmpDir;
+
+  const mod = await import("../../../build/routes/xref/terms.get.js");
+  route = mod.default;
+});
+
+afterAll(async () => {
+  if (origDataDir !== undefined) {
+    process.env.DATA_DIR = origDataDir;
+  }
+  if (tmpDir) {
+    await rm(tmpDir, { recursive: true, force: true });
+  }
+});
+
+function mockReq(query = {}) {
+  return { query };
+}
+
+function mockRes() {
+  const res = {
+    _status: 200,
+    _body: undefined,
+    _headers: {},
+    status(code) { res._status = code; return res; },
+    json(body) { res._body = body; return res; },
+    set(header, value) { res._headers[header] = value; return res; },
+    send(body) { res._body = body; return res; },
+  };
+  return res;
+}
+
+describe("xref/terms - server autocomplete", () => {
+  it("returns 400 when q is missing", () => {
+    const res = mockRes();
+    route(mockReq(), res);
+    expect(res._status).toBe(400);
+  });
+
+  it("returns 400 when q is too short", () => {
+    const res = mockRes();
+    route(mockReq({ q: "a" }), res);
+    expect(res._status).toBe(400);
+  });
+
+  it("returns prefix matches before infix-only matches", () => {
+    const res = mockRes();
+    route(mockReq({ q: "ev" }), res);
+    const results = res._body;
+    const firstInfix = results.findIndex(t => !t.toLowerCase().startsWith("ev"));
+    const lastPrefix = results.findLastIndex(t => t.toLowerCase().startsWith("ev"));
+    if (firstInfix !== -1) {
+      expect(lastPrefix).toBeLessThan(firstInfix);
+    }
+  });
+
+  it("returns prefix matches first", () => {
+    const res = mockRes();
+    route(mockReq({ q: "ev" }), res);
+    expect(res._status).toBe(200);
+    expect(Array.isArray(res._body)).toBeTrue();
+    expect(res._body.length).toBeGreaterThan(0);
+    for (const term of res._body) {
+      expect(term.toLowerCase()).toMatch(/ev/);
+    }
+  });
+
+  it("matches case-insensitively but preserves original case", () => {
+    const res = mockRes();
+    route(mockReq({ q: "eventtarget" }), res);
+    expect(res._body).toContain("EventTarget");
+  });
+
+  it("returns infix matches when prefix results are insufficient", () => {
+    const res = mockRes();
+    route(mockReq({ q: "signal" }), res);
+    expect(res._body).toContain("AbortSignal");
+    expect(res._body).toContain("abort signal");
+  });
+
+  it("respects the limit parameter", () => {
+    const res = mockRes();
+    route(mockReq({ q: "ev", limit: "3" }), res);
+    expect(res._body.length).toBeLessThanOrEqual(3);
+  });
+
+  it("caps limit at 50", () => {
+    const res = mockRes();
+    route(mockReq({ q: "ev", limit: "100" }), res);
+    expect(res._body.length).toBeLessThanOrEqual(50);
+  });
+
+  it("defaults limit to 15", () => {
+    const res = mockRes();
+    route(mockReq({ q: "ab" }), res);
+    expect(res._body.length).toBeLessThanOrEqual(15);
+  });
+
+  it("sets Cache-Control header", () => {
+    const res = mockRes();
+    route(mockReq({ q: "ev" }), res);
+    expect(res._headers["Cache-Control"]).toBeDefined();
+    expect(res._headers["Cache-Control"]).toMatch(/max-age=/);
+  });
+
+  it("returns empty array for no matches", () => {
+    const res = mockRes();
+    route(mockReq({ q: "zzzzzzz" }), res);
+    expect(res._body).toEqual([]);
+  });
+
+  it("handles mixed case query preserving original", () => {
+    const res = mockRes();
+    route(mockReq({ q: "ForeignObj" }), res);
+    expect(res._body).toContain("foreignObject");
+  });
+
+  it("normalizes array query params to first element", () => {
+    const res = mockRes();
+    route(mockReq({ q: ["event", "ignored"] }), res);
+    expect(res._status).toBe(200);
+    expect(Array.isArray(res._body)).toBeTrue();
+    expect(res._body.length).toBeGreaterThan(0);
+  });
+
+  it("returns 400 when array query param has short first element", () => {
+    const res = mockRes();
+    route(mockReq({ q: ["a", "event"] }), res);
+    expect(res._status).toBe(400);
+  });
+});