The surnames Pini, Pino, Pin, Pina and their numerous variants derive from the hypocoristic 'Pino', an affectionate or family form that abbreviates personal names such as Giuseppino (from Giuseppe), Filippino (from Filippo), or Iacopino (from Iacopo). The use of hypocoristics as a base for the formation of surnames was very common in Italy: from Giuseppe, the form Giuseppino > Pino; from Filippo, the form Filippino > Pino; and from Iacopo, Iacopino > Pino. Thus, different family branches may have adopted the surname Pino, later generating local or dialectal derivations such as Pini, Pinella, Pinato, among others.

The surname Pinardi, documented especially in Lombardy, could have two origins: on the one hand, from the same hypocoristic 'Pino' combined with the suffix -ardi, which indicates belonging or descent; and on the other, it could be the fusion of 'Pino' with the Germanic suffix -hard, with the sense of 'Pino the strong' or 'Giuseppe the strong'.

The variants Pinèlli, Pinella, Pinétti, Pinato, Pinalli, and others show the richness of regional suffixes or affectionate diminutives, often present in surnames of northern and central Italy. Some of these forms are very localized and reflect the phonetic evolution proper to certain regions.

Some variants such as Pinazzi, Pinétti, Pineschi or Pinésso, ending in -azzi, -etti, -eschi, reflect the influence of regional suffixes with a diminutive, affectionate or even patronymic value. The suffix -azzi usually has an affectionate or sometimes collective nuance in regions of northern Italy, while -ato, as in Pinato, may indicate origin or belonging. In the specific case of Pinato, as Rossoni clarifies, it is not a toponymic surname but a patronymic, that is, one that indicates descent or relation with a person called Pino, the hypocoristic form (aphaeresis) of Giuseppe.

Authors such as Emidio De Felice, P. Lastrico and E. Rossoni have documented these forms as common derivations from personal names widely used in the Italian Christian tradition.

The surname Pinna, although it may seem a phonetic or regional variant of Pini or Pina, has a different origin. In several regions, especially in Sardinia, Pinna derives directly from the Latin noun pinna, which means 'feather', 'fin' or 'point', and in toponymic contexts could refer to rises in the terrain or pointed forms of the landscape. In Sardinia it is one of the most diffused surnames and one with deep local roots.