na-adjective, noun
proud; triumphant; looking pleased with oneself
Describes someone's expression or manner when they are visibly proud or self-satisfied, often after a success or when showing off.
彼はテストで満点を取って、得意げな顔をしていた。
He had a proud look on his face after getting a perfect score on the test.
彼女は新しいドレスを見せびらかしながら、
She walked around proudly, showing off her new dress.
Formed from 得意 (とくい, 'pride' or 'strong point') + the suffix げ, which attaches to adjectives and nouns to mean 'looking like' or 'seeming'.