/ˈsɪnjuː/
sinew
BrE /ˈsɪnjuː/
NAmE /ˈsɪnjuː/
[C, U]
a strong band of tissue in the body that joins a muscle to a bone
[usually pl.] (literary)
a source of strength or power
strain every ˈnerve/ˈsinew (to do sth)
(formal)
to try as hard as you can to do sth