Thinornis is a genus of plovers, a group of wading birds in the family Charadriidae, in the order Charadriiformes. 

The two below species formerly belonged to the genus Charadrius.

1/ Long-billed plover (Choi choi lớn, Thinornis placidus)

2/ Little ringed plover (Choi choi nhỏ, Thinornis dubius) 
The specific dubius is Latin for doubtful, since Sonnerat, writing in 1776, thought this bird might be just a variant of common ringed plover.

Charadrius, Charadriidae or Charadriiformes comes from the Ancient Greek kharadrios, meaning a bird found in river valleys or ravines ((kharadra) being ravine), and was later adopted into Late Latin. The Latin word Thinornis described a yellowish bird mentioned in the Vulgate Bible.

The genus name Thinornis is derived from Ancient Greek: "this" or "thinos" meaning "beach" or "sand," combined with "ornis" meaning "bird". Therefore, Thinornis literally translates to "beach bird" or "sand bird".