'unshortenable' originates from the prefix 'un-' meaning 'not' and the root 'shorten' meaning 'to make shorter', combined with the suffix '-able' indicating capability.

'unshortenable' evolved from the combination of 'un-' and 'shorten', with the addition of '-able' to form the modern English word.

Initially, it meant 'not capable of being shortened', and this meaning has remained consistent in modern usage.