After a series of hairpin turns, the trees began to thin and the sky expanded.
At night bats flit through the gaps at the top of the wall, do hairpin turns in the air, and exit again without slowing.
British Dictionary definitions for hairpin
hairpin
/ˈhɛəˌpɪn/
noun
1.
a thin double-pronged pin used by women to fasten the hair
2.
(modifier) (esp of a bend in a road) curving very sharply
Word Origin and History for hairpin
n.
also hair-pin, 1788 (two words), from hair + pin (n.). A hairpin turn, etc., is from 1906. Hairpin (or clothespin) was American English slang for "person" c.1880-1910, especially in the expression "That's the kind of hairpin I am."