The name Quasimodo has a deeper resonance; it sets up a touchstone for judging the actions of all of Hugo’s characters, especially Quasimodo and Frollo.
Frollo chose the name because he found the child on Quasimodo Sunday, the Sunday after Easter. The introit (processional chant) appointed for that Sunday begins with the words "Quasi modo." The Introit is taken from I Peter 2:2: Quasi modo geniti infantes rationale sine dolo lac concupiscite ut in eo crescatis in salutem. "As newborn infants, desire the rational, guileless milk [of the Spirit], so that by it you may grow into salvation." Frollo of course knows the meaning of the Latin, and no doubt feels it is appropriate to name an infant after this New Testament verse.
But this Bible verse resonates throughout Hugo’s novel. God’s children are called on to be like newborn babies, whose desires are rational and without guile. Who in Hugo’s novel has rational desires? Who is without guile? Who, in the end, grows into salvation?
There may be a pun in the name Quasimodo. The Latin words "quasi" and "modo" can also mean "almost" and "the standard measure." Quasimodo seems to be "almost the standard measure" of a human being.