Sinclair \s(i)-nc-lair, sin-clair\ as a boy's name is pronounced sin-KLARE. It is of English origin, and the meaning of Sinclair is "from Saint-Clair". Based on the name of a place in northern France. See also Santana and Seymour. Authors Sinclair Lewis, Upton Sinclair.

Sinclair has 3 variant forms: Sinclaire, Sinclare and Synclair.