Hirsute

hirsute is an adjective, mostly used to describe hair or beard, that means tousled.
un cheveu / des cheveux (plural, the 'x' is silent) = hair
une barbe (the 'e' is silent) = a beard

avoir les cheveux hirsutes = avoir les cheveux en bataille = to have tousled hair.

Literally, the second expression means "to have one's hair in a battle"