arch
back
She arched her back slightly to create a more graceful pose.
The horse was arching its back and groaning in agony.
High jumpers will arch their backs to make sure their bodies do not remove the bar.
SMART Vocabulary: related words and phrases
Bending, twisting and curving
ball up
bendy
bent
bowed
buckle
distortion
entwine
flex
flexion
flexural
swirling
swirlingly
swoopy
tangle
tangled
wrap something around someone/something
wriggle
wristy
writhe
zigzag