pester vs torment

pester is not a noun while torment is a noun.

Word	Noun	Adjective	Verb	Adverb
pester	No	No	Yes	No
torment	Yes	No	Yes	No

As verbs, torment is a hypernym of pester; that is, torment is a word with a broader meaning than pester:

Other hypernyms of pester include bedevil, crucify, dun, frustrate, rag.

pester (noun)	torment (noun)
	the act of harassing someone
	a severe affliction
	intense feelings of suffering; acute mental or physical pain
	extreme mental distress
	a feeling of intense annoyance caused by being tormented
	unbearable physical pain

pester (verb)	torment (verb)
annoy persistently	subject to torture
	torment emotionally or mentally
	treat cruelly