'agate-trimmed' originates from English, specifically the compound of 'agate' and 'trimmed'. 'Agate' itself comes into English via Old French 'agate' from Latin 'achates' (from Greek 'Akhátes'), the name associated with the stone; 'trimmed' is the past participle of 'trim', from Middle English (from earlier Germanic/Old English roots) meaning 'to make neat or decorate'.

'agate' changed from Greek 'Akhátes' to Latin 'achates' and Old French 'agate', eventually entering modern English as 'agate'. The verb 'trim' appeared in Middle English (as 'trimmen'/'trim') meaning 'to arrange or adorn', and its past participle 'trimmed' combined with 'agate' to form the descriptive compound 'agate-trimmed'.

Initially, 'agate' referred to the specific semiprecious stone and 'trim' meant 'to make neat or decorate'; over time the compound 'agate-trimmed' came to mean specifically 'having an edge or decoration made of agate'.