If a speech, a thank-you, or a piece of writing is fulsome, there is too much praise in it, and it starts to sound false. Fulsome praise is the pair of words you will see again and again. The speaker lays it on so thick — how wonderful you are, how deeply grateful they are — that you cannot quite believe them. It feels a little oily, as if they want something, or cannot stop themselves. This is the meaning a learner’s dictionary wants you to learn, and it is the safest one for exams and careful writing. Though actually, the word has had a messy life, and even native speakers fight about it. Long ago it simply meant “full, abundant”, which sounds kind. It later meant something like “plump” or “overfed”, and then picked up a worse smell — “offensive, sickening” — helped along by the older word foul; for a time people even spelled it foulsome. In the centuries since, all of those colours have lingered. You will still hear educated people say fulsome thanks when they only mean “generous, plenty of thanks”, and some older usage books get quite cross about that. So the tidy classroom answer is “so full of praise that it feels fake”. The messy truth is that some careful writers insist on that, and some everyday speakers still hear “full and warm”. If you want to say thanks were warm and plenty, say generous or warm instead, and nobody will argue with you.

過分恭維的、溢美得顯得假（不是「充分、真心」）