Headcase

Part of speech: noun

Definitions

1. A person whose mental state is unstable, unpredictable, or unreliable in a way that affects their behavior
2. Someone regarded as mentally unbalanced or prone to erratic and irrational conduct
3. A person considered mentally unstable or emotionally unpredictable in their actions and responses

Etymology: The word "headcase" is a compound of "head" and "case," with "head" tracing back through Old English "hēafod" and Proto-Germanic "haubudą" to a Proto-Indo-European root "*káput," the same ancestor behind words like "capital" and "cap." Its first element has been in English since the earliest records, long before any idea of a mind in trouble was attached to it. The "case" element is a separate and more recent story: it entered English from Old French "cas," which came from Latin "casus," meaning a fall or an occurrence, and it earned its way into the sense of a person, an instance, or a legal matter over several centuries. Put together, the two parts make a compound whose meaning is usually summed up as someone whose head, or mind, is a "case," meaning a problem to be handled. The exact date this combination first appeared in print is not something this account can confirm, so the word's pedigree is best understood as a modern pairing of old and well-documented parts rather than a single coinage with a known author.

Synonyms: eccentric, oddball, weirdo

Antonyms: conformist