Well, basically, another word for <u>petulant</u> will be "sulky", and that's a person who's irritable. Another word for <u>somnolent</u> will be "sleepy". Another word for <u>recalcitrant</u> can be "uncooperative". A synonym for <u>supplement </u>can be "additional" and for recreant "coward". A<u> pertinent</u> person/thing can also be called "Relevant" or "to the point", and a <u>resilient </u>person can be considered a "strong in attitude" person. Another word for <u>significant</u> can be the same one you mention, "important" "relevant".