Real Dictionary

wren
countable noun: A wren is a very small brown bird. There are several kinds of wren.

wren in American English
any of a large family (Troglodytidae) of small, insect-eating passerine birds having a long bill, rounded wings, and a stubby, erect tail; esp., the house wren (Troglodytes aedon), that often nests in birdhouses in North America
noun: any of numerous small, active songbirds of the family Troglodytidae, esp Troglodytes troglodytes, of the Northern Hemisphere, having dark-brown plumage barred with black and a short, upright tail

Wren in American English 1
a member of the (British) Women's Royal Naval Service

Wren in American English 2
Sir Christopher1632-1723; Eng. architect
noun: a member of the Wrens

wren in British English
noun: any small brown passerine songbird of the chiefly American family Troglodytidae, esp Troglodytes troglodytes (wren in Britain, winter wren in the US and Canada). They have a slender bill and feed on insects

Wren in British English 1
noun: (in Britain and certain other nations) a member of the former Women's Royal Naval Service

Wren in British English 2
noun: Sir Christopher. 1632–1723, English architect. He designed St Paul's Cathedral and over 50 other London churches after the Great Fire as well as many secular buildings