The word 'Trinidadian' is a modern English formation directly derived from the name of the Caribbean island, Trinidad. The island was named 'La Isla de la Trinidad' (The Island of the Trinity) by Christopher Columbus in 1498, reflecting the Christian doctrine. The name 'Trinidad' originates from the Latin 'trinitas', meaning a group of three or the Holy Trinity, itself from 'trinus' meaning 'threefold'. The English suffix '-ian', with its roots in Latin '-ianus', was appended to create a demonym, following a common pattern in English for forming words denoting origin or affiliation (e.g., Canadian, Brazilian). Thus, the term's logic flows from a religious concept used for geographical naming to a straightforward linguistic marker of nationality and cultural identity.

The word is a toponymic demonym formed from the proper noun 'Trinidad' with the addition of the English adjectival/nominal suffix '-ian'. 'Trinidad' itself is a Spanish word meaning "Trinity", from the Latin 'trinitas' (triad, threefold). The suffix '-ian' is of Latin origin via Old French, used to form adjectives and nouns meaning "belonging to" or "relating to".