The boasters in the office who always talk about their achievements are really annoying.

boasters 是动词 boast（自夸、吹嘘）加后缀 -er 构成的名词复数形式，表示"自夸者、吹嘘者"。后缀 -er 通常表示"做某事的人"。 boast 本身的意思是"夸耀、吹嘘"，指过分夸大自己的成就或能力。