This word appears only one time in all of scripture.
הִתְאֹשָׁ֑שׁוּ hitoshashu
Strong’s #377. “Denominative from ‘iysh; to be a man, i.e. Act in a manly way — show (one) self a man.”
Remember this one, and become men, turn back those-who-rebel upon the heart.
Isaiah 46:8 RBT
The verb is in the Hithpo’el form which is a reflexive verb form that literally means “to make yourself a man”. Notice how the second imperative clause can be interpreted in two ways, i.e. the participle verb “those-who-rebel” could mean themselves or others.