This entry examines a group of surnames derived from the given name Giacomo. In some regions of Italy, the contraction of Giacomo —that is, the loss of a syllable— took a particular form: Iaco, from which a number of suffixed variants derived. The addition of suffixes gives the surname different connotations.

The name Jacopo, derived from the Hebrew Giacobbe, together with the Greco-Byzantine variant Giacomo (very widespread during the Middle Ages), gave rise to a great variety of surnames of religious inspiration. Ya'āgob is the name of the patriarch Jacob in the Old Testament, and of the apostles James the Greater and James the Less in the New Testament. The Hebrew name, in turn, derives from Yah, an abbreviation of Yahweh = God, and probably gob = to protect, hence "God has protected". Giacomo, Giacobo, Giacopo and Giacobbe are, in origin, the same name. It is a male given name, corresponding to English James.

In some regions, the contraction of Giacomo took its own particular form: Iaco, from which a number of suffixed variants derived —Iachi, Iaci, Iachelli, and so on— alongside the doubly suffixed derivations: Iacomelli, Iacometti, Iacometta, Iacomini, and others.

Iacono, Lo Iacono and Loiacono deserve separate mention, since they would derive from the position held by their bearer: that of a deacon in the church.

Other surnames derived from variants of the name Giacomo are those formed from Giaco.

Variants identified in Italy

Iachelli, Iachello, Iachetta, Iachetti, Iachi, Iachini, Iachino, Iaci, Iacini, Iacino, Iaco, Iacobacci, Iacobbe, Iacobbi, Iacobelli, Iacobellis, Iacobini, Iacobino, Iacobitti, Iacobo, Iacobone, Iacoboni, Iacobucci, Iacolo, Iacomelli, Iacometta, Iacometti, Iacomi, Iacomini, Iacomino, Iacomo, Iacomoni, Iacopetti, Iapichelli, Iapichella, Iappichini, Iacopini, Iacopino, Iacopo, Iacopucci, Iacovacci, Iacovella, Iacovelli, Iacoviello, Iacovini, Iacovo, Iacovone, Iacovucci, Iacuvelli, Iacuelli, Iacovuzzi, Iacovizzi, Iacuissi, and also Dello Iacovo, De Iaco.