What's a word for "toughish"?
Brutish
Resembling, befitting, or being typical of a brute [Webster's]
Brutish is good for ending in -ish. I'm not sure how much of a requirement that is. Here are a few that don't end in -ish that I think work really well for thugs (links go to Dictionary.com definitions):
Pugnacious - this is my favorite; a person who is ready to fight, it also reminds me of this question.
Bellicose - this means warlike; someone who is loud and blustering
Belligerent - another favorite; this is how I imagine I behave when I am aggressively drunk
All of the above focus on the thuggish-ness of thugs in the sense of people who are mainly muscle at the command of their leader. Otherwise, if you are set on -ish, then my last suggestion is
- Churlish - a mean person.
This word is more broadly applicable to the surly, narrow-minded, ill-natured aspect of thuggery. It would not apply to thugs with a sense of humor, for instance.