Sneering is a verb.
She sneered at him.The crowed sneered at the unpopular band.
Deadpool is a great movie. You can see ryan renolds sneered through camera!
she sneered At His Attempt to Speak French
Mary sneered at the boy making funny faces.
You could say 'he said sneeringly' which is an example of the adverb, but this is better written as 'he sneered'.
Not sure, but can any of this words be used?: Contemptuous or scornfully
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
sneered