Standard Lemma guide

wacko

adj · intj · noun · 4 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • UK: /ˈwæ.kəʊ/
  • US: /ˈwæ.koʊ/
  • rhymes with -ækəʊ
  • US: Recorded audio is listed in the source snapshot.
  • CMU ARPABET: W AE1 K OW0 Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.

1

adj

Meaning 1

Amusingly eccentric or irrational.

Definition source: English Wiktionary via Wiktextract

Usage: derogatory, informal, slang

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: kooky, oddballish, pixilated, aberrant, abnormal, anomalous, balmy, barmy, bizarre, crackpot, cranky, eccentric, eccentrical, erratic, excentrical, extraordinary, far-out, freakish, heteroclite, idiocentric, idiosyncratic, irregular, kookish, nutbar, odd, off-centre, outlandish, outré, peculiar, queer, quirky, quizzy, spacy, squirrelly, uncommon, wacky, weird, whimsical, whimsome, wifty, Wodehousian, Wonkaesque

Antonyms: none provided

2

intj

Meaning 2

Hurrah!

Definition source: English Wiktionary via Wiktextract

Usage: UK, dated

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: get in, huzzah, woo hoo, aah, alright, 'ave it, aww yeah, boo-ya, booyah, cowabunga, hoo, hoorah, hooray, hurrah, hurray, oh yeah, OMG, result, w00t, wacko, wahoo, whee, woo, wooh, woohay, woohoo, woop woop, whoo, whoop-de-doo, whoopee, yahoo, yay, yeah, yeehaw, yes, yippee, yippee-ki-yay, you beauty, zip-a-dee-doo-dah

Antonyms: none provided

3

noun

Meaning 3

An amusingly eccentric or irrational person.

Definition source: English Wiktionary via Wiktextract

Usage: derogatory, slang

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: kook, odd duck, weirdo, bizarro, coot, crackpot, crank, eccentric, freak, glaik, hard case, live one, nutbag, nutbar, nutcase, nutter, oddball, oddity, odd bod, odd fish, queerdo, queer fish, rum, strange bird, strange fish, strangeling, wack, wacko, weirdie, weirdling, wild man, wingnut

Antonyms: none provided

4

noun

Meaning 4

a person who is regarded as eccentric or mad

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: nutter, whacko

Antonyms: none provided

Broader terms: eccentric, eccentric person, flake, oddball, geek

History

Etymology

Etymology tree English whack Proto-Indo-European *-kos Proto-Germanic *-gaz Proto-West Germanic *-g Old English -iġ Middle English -y English -y English wack(y) English -o English wacko From wack(y) + -o.

Across languages

Translations

5 source translations are retained for this English entry.

  • German: durchgeknallt — amusingly eccentric or irrational
  • German: spinnert — amusingly eccentric or irrational
  • German: schrill — amusingly eccentric or irrational
  • Russian: чудной (čudnoj) — amusingly eccentric or irrational
  • Swedish: knäppgök — amusingly eccentric or irrational