Common tern (Nhàn, Sterna hirundo) 

The common tern (Sterna hirundo) is a seabird in the family Laridae.
The breeding ground is in temperate and subarctic regions of Europe, Asia and North America. 
The bird is strongly migratory, wintering in coastal tropical and subtropical regions.

Charadriiformes, Charadriidae, Charadrius: Late Latin word for a yellowish bird mentioned in the fourth-century Vulgate; from Ancient Greek kharadrios a bird found in ravines and river valleys (kharadra, "ravine").

Laridae:from Ancient Greek laros or Latin larus, which appears to have referred to a gull or other large seabird.

The genus name Sterna is derived from Old English "stearn", "tern".

The Latin for swallow is hirundo, and refers here to the tern's superficial likeness to that unrelated bird, which has a similar light build and long forked tail. This leads to the informal name "sea swallow".