What is the meaning of Guppy?

A tiny freshwater fish, Poecilia reticulata, popular in home aquariums, that usually has a plain body and black or dark blue tail for the females and a more colorful tail for the males.

Any tiny fish.

A tube holding paintballs before they are loaded into the gun.

A hold across the palm of the hand rather than the fingertips.

guppy

Source: wiktionary.org