威張(いば)るto put on airs, to act big, to throw one's weight about, to be overbearing, to be domineering, to be bossy, to be pushy, to be proud, to be haughty, to be arrogant, to swagger, to boast, to brag

あの上司(じょうし)はいつも部下(ぶか)に威張(いば)っているので、人気(にんき)がない。

That boss is always bossy to his subordinates, so he's not popular. {to put on airs, to act big, to throw one's weight about, to be overbearing, to be domineering, to be bossy, to be pushy, to be proud, to be haughty, to be arrogant, to swagger, to boast, to brag}

そのクラスメイトは「家(いえ)に最新(さいしん)のゲーム機(き)がある」と威張(いば)っています。

That classmate is boasting, 'I have the latest game console at home'. {to put on airs, to act big, to throw one's weight about, to be overbearing, to be domineering, to be bossy, to be pushy, to be proud, to be haughty, to be arrogant, to swagger, to boast, to brag}

先生(せんせい)：「宿題(しゅくだい)が終(お)わったら、校庭(こうてい)で威張(いば)って遊(あそ)んでもいいですよ。」

Teacher: 'Once you're done with your homework, it's fine to play and show off in the schoolyard.' {to put on airs, to act big, to throw one's weight about, to be overbearing, to be domineering, to be bossy, to be pushy, to be proud, to be haughty, to be arrogant, to swagger, to boast, to brag}

親(おや)の財力(ざいりょく)抜(ぬ)きで威張(いば)ることが出来(でき)ないなんて、みっともないです。

It's disgraceful that you can't show off without relying on your parents' wealth. {to put on airs, to act big, to throw one's weight about, to be overbearing, to be domineering, to be bossy, to be pushy, to be proud, to be haughty, to be arrogant, to swagger, to boast, to brag}

その同僚(どうりょう)は私(わたし)がちょっとしたミスをした事(こと)を契機(けいき)に威張(いば)るようになりました。

That colleague started to act arrogant after I made a minor mistake. {to put on airs, to act big, to throw one's weight about, to be overbearing, to be domineering, to be bossy, to be pushy, to be proud, to be haughty, to be arrogant, to swagger, to boast, to brag}