The term 'irritating one' can be described by three crossword solutions: VEXER (5 letters), PEST (4 letters), and TWERP (5 letters). VEXER is a verb meaning to annoy or bother someone, while PEST is a noun referring to an annoying person or animal. TWERP is an informal term for a person who is considered to be insignificant or contemptible. All three words are used to describe someone who is irritating or annoying.