fee splitting vs defrayal

fee splitting and defrayal both are nouns.

Word	Noun	Adjective	Verb	Adverb
fee splitting	Yes	No	No	No
defrayal	Yes	No	No	No

As nouns, defrayal is a hypernym of fee splitting; that is, defrayal is a word with a broader meaning than fee splitting:

fee splitting: payment (usually by doctors or lawyers) of part of the fee in return for the referral
defrayal: the act of paying money

Other hypernyms of fee splitting include defrayment, payment.

fee splitting (noun)	defrayal (noun)
payment (usually by doctors or lawyers) of part of the fee in return for the referral	the act of paying money