F. De Laurentiis notes that this surname derives from several nicknames and trade names formed from sega ("saw, sickle") or from the verb segare ("to cut with the saw, to reap"), alluding to one who cut trees or wood with the saw, worked in a sawmill or reaped the grass. De Laurentiis adds that some Venetan surnames may have as their base the place names Sega —in the Verona, Treviso or Venice areas— or Seghe, in the Vicenza area.

R. Brondolo qualifies this interpretation: he considers that the surname points back to a trade name linked to reaping and not to the saw, which would point to peasants and mountain workers rather than to carpenters or sawyers. As evidence, he cites the dialect form siè l'èrba, "to reap the grass," proper to northern Italy.