Optics in Italian

Il fascio collimato is the collimated beam, and the verb inside it has the strangest history of anything on this page. Latin had collineare, built on com- and linea: to bring into line. In early printed editions of Cicero that word was misread and set as collimare, with an m, and optics — a young science hungry for Latin — picked up the wrong form and kept it. « To collimate » is therefore a compositor’s slip that hardened into a technical term, while « collineate », the form that ought to have survived, sits unused in a corner of geometry. Italian inherited the same misprint as collimare, and then did something English never did with it: it let the word out of the laboratory. In everyday Italian, collimare means to tally, to agree, to line up in the sense of matching — le due versioni non collimano, the two accounts do not match, or i dati collimano, the figures agree. So a reader who meets collimare away from an optical bench should not look for a beam: what is being brought into line there is two statements.