The Spanish word 'calamar' (meaning 'squid') comes from the Italian 'calamaro', which had the dual meaning of 'inkwell' and 'squid'. This Italian word evolved from 'calamo' (meaning 'writing pen') in Old Italian, which in turn came from the Latin word 'calamus' meaning 'reed' or 'writing pen'.

The semantic evolution from 'reed/writing pen' to 'squid' is quite fascinating and logical: since ancient times, reeds were hollowed out and used as writing implements, often dipped in ink. The connection to squid comes from the fact that these sea creatures produce ink as a defense mechanism. The Italian word 'calamaro' beautifully captures this connection by referring to both an inkwell and the ink-producing squid, before being borrowed into Spanish as 'calamar' specifically for the sea creature.

A related Spanish word is 'cálamo', which maintains the original Latin meaning of 'reed' or 'writing pen'. While 'cálamo' is not as commonly used in modern Spanish as 'calamar', understanding this connection helps explain how a word for a writing implement eventually came to name the ink-producing sea creature.

English speakers might recognize this etymology in the word 'calamus', which can refer to a species of reed plant or the hollow shaft of a feather. This comes from the same Latin root as 'calamar'. Another related English word is 'calamari', which is borrowed from Italian and is commonly used in English to refer to squid, especially as a food item on menus.