box end wrench

English Thesaurus

1. a wrench with a closed loop (a socket) that fits over a nut or bolt head (noun.artifact)

hypernym	:	spanner, wrench,
definition	:	a hand tool that is used to hold or twist a nut or bolt (noun.artifact)

part holonym	:	socket,
definition	:	receptacle where something (a pipe or probe or end of a bone) is inserted (noun.artifact)