'berthable' is a Modern English formation combining the noun 'berth' (from Middle English 'berth', referring to a ship's place or sleeping place) with the adjectival suffix '-able', which ultimately derives from Latin 'abilis' meaning 'able to be'.

'berth' in Middle English denoted a ship's place to sleep or moor; in Modern English this noun combined with the productive suffix '-able' to form technical adjectives like 'berthable' meaning 'able to be given a berth.'

Initially 'berth' meant 'a place on a ship, a place to tie up or sleep'; with the addition of '-able' the meaning shifted to describe something 'capable of being berthed' in contemporary usage.