Sycophantic is the adjective: it describes praise, behaviour, writing or people that flatter a powerful person far too much, in the hope of getting something back. You put it in front of the thing that carries the flattery — 'a sycophantic smile', 'a sycophantic email', 'sycophantic laughter', 'the sycophantic press' — or in front of a person: 'his sycophantic assistant'. It always disapproves. Because it is an adjective, it lets you criticise the behaviour without going all the way to calling a person a sycophant, which sounds harsher; 'that review was a bit sycophantic' is a lighter, more usable sentence than 'that reviewer is a sycophant'. It works with degree words — 'faintly sycophantic', 'utterly sycophantic'. It is formal and mostly written; in conversation people say 'he was totally sucking up' or 'that was such a kiss-up move'. The adverb 'sycophantically' exists ('he laughed sycophantically') but sounds heavy, so most writers rearrange the sentence instead. A useful test for students: if you removed the hope of reward, would the praise still be there? If yes, it is just admiration. If the praise would vanish, it is sycophantic.

諂媚的、逢迎拍馬的、阿諛的。形容「那種話／那封信／那個笑容」很會拍馬屁。台灣口語會說「很會拍馬屁的」「很會巴結的」。注意它是形容詞，罵的是那個行為或那種語氣，比直接說對方是「馬屁精」稍微含蓄一點。