diff --git a/src/1-one/lexicon/compute/single-word.js b/src/1-one/lexicon/compute/single-word.js
new file mode 100644
index 0000000..9d79fa9
--- /dev/null
+++ b/src/1-one/lexicon/compute/single-word.js
@@ -0,0 +1,42 @@
+const prefix = /^(under|over|mis|re|un|dis|semi|pre|post)-?/
+// anti|non|extra|inter|intra|over
+const allowPrefix = new Set(['Verb', 'Infinitive', 'PastTense', 'Gerund', 'PresentTense', 'Adjective', 'Participle'])
+
+// tag any words in our lexicon
+const checkLexicon = function (terms, i, world) {
+  const { model, methods } = world
+  // const fastTag = methods.one.fastTag
+  const setTag = methods.one.setTag
+  const { lexicon } = model.one
+
+  // basic lexicon lookup
+  const t = terms[i]
+  const word = t.machine || t.normal
+  // normal lexicon lookup
+  if (lexicon[word] !== undefined && Object.hasOwn(lexicon, word)) {
+    setTag([t], lexicon[word], world, false, '1-lexicon')
+    return true
+  }
+  // lookup aliases in the lexicon
+  if (t.alias) {
+    const found = t.alias.find(str => Object.hasOwn(lexicon, str))
+    if (found) {
+      setTag([t], lexicon[found], world, false, '1-lexicon-alias')
+      return true
+    }
+  }
+  // prefixing for verbs/adjectives
+  if (prefix.test(word) === true) {
+    const stem = word.replace(prefix, '')
+    if (Object.hasOwn(lexicon, stem) && stem.length > 3) {
+      // only allow prefixes for verbs/adjectives
+      if (allowPrefix.has(lexicon[stem])) {
+        // console.log('->', word, stem, lexicon[stem])
+        setTag([t], lexicon[stem], world, false, '1-lexicon-prefix')
+        return true
+      }
+    }
+  }
+  return null
+}
+export default checkLexicon
diff --git a/tests/one/lexicon/core-lexicon.test.js b/tests/one/lexicon/core-lexicon.test.js
new file mode 100644
index 0000000..8d24fdf
--- /dev/null
+++ b/tests/one/lexicon/core-lexicon.test.js
@@ -0,0 +1,86 @@
+import test from 'tape'
+import nlp from '../_lib.js'
+const here = '[one/lexicon] '
+
+test('addWords side-load:', function (t) {
+  let lex = {
+    bigg: 'Size',
+    'bigg apple': 'Town',
+  }
+  const _nlp = nlp //.fork()
+  let doc = _nlp('it was bigg')
+  t.equal(doc.has('(#Size|#Town)'), false, here + 'none-on-init')
+
+  doc = _nlp('it was bigg', lex)
+  t.equal(doc.has('#Size'), true, here + 'single-word')
+  doc = _nlp('the bigg apple', lex)
+  t.equal(doc.has('#Town'), true, here + 'found-multi-word')
+  t.equal(doc.has('#Size'), false, here + 'no-single-word')
+
+  doc = _nlp('it was bigg')
+  t.equal(doc.has('#Size'), true, here + 'lex-persists')
+
+  lex = {
+    bigg: undefined,
+    'bigg apple': undefined,
+  }
+  doc = _nlp('it was bigg', lex)
+  t.equal(doc.has('#Size'), false, here + 'lex-removed')
+  doc = _nlp('the bigg apple', lex)
+  t.equal(doc.has('#Town'), false, here + 'multi-lex-removed')
+
+  t.end()
+})
+
+test('lexicon compute:', function (t) {
+  const words = {
+    'captain obvious': 'Captain',
+  }
+  const doc = nlp('it was captain obvious', words)
+  const m = doc.match('#Captain+')
+  t.equal(m.text(), 'captain obvious', here + 'multi-word')
+  t.end()
+})
+
+test('tricky lexicon:', function (t) {
+  const lexicon = {
+    'bed bath and beyond': 'Organization',
+  }
+  const _nlp = nlp //.fork()
+  let r = _nlp('shopping at Bed Bath and Beyond, the store', lexicon)
+  let str = r.match('#Organization+').out('normal')
+  t.equal(str, 'bed bath and beyond', here + 'four-word')
+
+  r = _nlp('shopping at Bed Bath and-beyond the store', lexicon)
+  str = r.match('#Organization+').out('normal')
+  t.equal(str, 'bed bath and beyond', here + 'partially-hyphenated-word')
+
+  r = _nlp('shopping at Bed-bath and-beyond the store', lexicon)
+  str = r.match('#Organization+').out('normal')
+  t.equal(str, 'bed bath and beyond', here + 'many-hyphenated-word')
+  t.end()
+})
+
+test('apostrophe lexicon:', function (t) {
+  const lex = {
+    "queen anne's lace": 'Flower',
+    "applebee's": 'Restaurant',
+  }
+  let doc = nlp(`i went to applebee's for dinner`, lex)
+  t.equal(doc.has(`#Restaurant`), true, here + 'lexicon w/ apostrophe')
+
+  doc = nlp(`Queen Anne's lace`, lex)
+  t.equal(doc.has(`#Flower`), true, here + 'multi lexicon w/ apostrophe')
+  t.end()
+})
+
+test('long lexicon:', function (t) {
+  nlp.addWords({ 'new york yankees are cool and not bad': 'Long' })
+  let doc = nlp('the new york yankees are cool and smart')
+  t.equal(doc.has('#Long'), false, here + 'missed-long')
+
+  doc = nlp('the new york yankees are cool and not bad')
+  t.equal(doc.has('#Long'), true, here + 'found-long')
+
+  t.end()
+})