'bottle-shaped' is a Modern English compound of the noun 'bottle' and the past-participle/adjective-forming element 'shaped' (from the verb 'shape'). 'bottle' itself originates from Old French 'boteille', from Late Latin 'butticula' (diminutive of 'buttis', meaning 'cask' or 'container'); 'shape' comes from Old English (from verbs and nouns meaning 'form' or 'create') ultimately from Proto-Germanic *skap-.

'bottle' passed from Late Latin 'butticula' → Old French 'boteille' → Middle English 'botel' → Modern English 'bottle'. 'shape' developed from Old English roots (forms meaning to make or form) into Middle English 'shape' and the modern verb/noun. The compound adjective 'bottle-shaped' formed in Modern English by combining the noun and the past participle/adjective 'shaped'.

Originally the elements referred separately to a 'container' ('bottle') and the act or result of forming ('shaped'); when combined they have meant 'having the form of a bottle' and this descriptive meaning has remained stable in modern usage.