hairpin

hair·pin   (hâr'pĭn')    n.   A thin cylindrical strip of metal or other material bent in the shape of a long U, used to secure a hairdo or headdress. Something shaped like a hairpin, especially a sharp turn in a road.

Main Entry: hair·pin
Pronunciation: 'ha(&)r-"pin, 'he(&)r-
Function: noun
: a region in single-stranded RNA or DNA that is double-stranded dueto pairing between purine and pyrimidine bases in adjacent sequences of the RNA or DNA that are complementary and inverted called also hairpin loop