rag vs pester

rag is a noun but pester is not a noun.

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

As verbs, pester is a hyponym of rag; that is, pester is a word with a more specific, narrower meaning than rag:

Other hyponyms of rag include madden, hamstring, badger, beleaguer, bug, tease, oppress, persecute.

rag (noun)	pester (noun)
a boisterous practical joke (especially by college students)
a small piece of cloth
newspaper with half-size pages
music with a syncopated melody (usually for the piano)
a week at British universities during which side-shows and processions of floats are organized to raise money for charities

rag (verb)	pester (verb)
break into lumps before sorting	annoy persistently
censure severely or angrily
harass with persistent criticism or carping
play in ragtime
treat cruelly
cause annoyance in; disturb, especially by minor irritations