deductible vs allowable

deductible is a noun but allowable is not a noun.

Word	Noun	Adjective	Verb	Adverb
deductible	Yes	Yes	No	No
allowable	No	Yes	No	No

deductible (noun)	allowable (noun)
a clause in an insurance policy that relieves the insurer of responsibility to pay the initial loss up to a stated amount
(taxes) an amount that can be deducted (especially for the purposes of calculating income tax)

deductible (adjective)	allowable (adjective)
acceptable as a deduction (especially as a tax deduction)	that may be permitted especially as according to rule
	deserving to be allowed or considered
	deductible according to the tax laws