say it: in-SAHM-nee-ak
insomniac is a noun and adjective meaning "someone who cannot sleep". It carries 2 recorded senses.
someone who cannot sleep
experiencing or accompanied by sleeplessness
“insomniac old people”
“insomniac nights”
“lay sleepless all night”
“twenty watchful, weary, tedious nights”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for insomniac come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.