treat vs ill-treat

treat is a noun but ill-treat is not a noun.

Word	Noun	Adjective	Verb	Adverb
treat	Yes	No	Yes	No
ill-treat	No	No	Yes	No

As verbs, ill-treat is a hyponym of treat; that is, ill-treat is a word with a more specific, narrower meaning than treat:

treat (noun)	ill-treat (noun)
an occurrence that causes special pleasure or delight
something considered choice to eat

treat (verb)	ill-treat (verb)
provide treatment for	treat badly
subject to a process or treatment, with the aim of readying for some purpose, improving, or remedying a condition
regard or consider in a specific way
act on verbally or in some form of artistic expression
engage in negotiations in order to reach an agreement
provide with choice or abundant food or drink
provide with a gift or entertainment
interact in a certain way