'unproclaimable' originates from English, formed by the negative prefix 'un-' + 'proclaimable', where 'un-' meant 'not', 'proclaim' comes from Latin 'proclamare', and suffix '-able' meant 'capable of'.

'proclaim' comes from Latin 'proclamare' ('pro-' meaning 'forth' and 'clamare' meaning 'to shout'); it passed into Old French as 'proclamer' and into Middle English before forming adjectives with '-able' and later compounds with 'un-'. The modern adjective 'unproclaimable' is a recent English formation built from these elements.

Initially, 'proclaim' meant 'to cry out' or 'to call forth'; over time it came to mean 'to declare or announce publicly.' 'Unproclaimable' therefore evolved to mean 'not able or suitable to be publicly declared.'