costlier
Yes, it is. It is the comparative form of the adjective costly (i.e. more costly).
costlier
Yes it is. It is the adverb form of the adjective expensive, and means in a costly, lavish or extravagant manner.
Yes, costly is an adjective. E.g. It was a costly mistake. (One that was expensive to fix, or that led to other bad consequences.)
costlier, costliest
No, it is not (despite the LY ending). The word costly is an adjective (expensive, high-priced).
Costliest is an adjective. It is the superlative of costly.
The adjective form of concept is conceptual.The adjective form of conception is conceptional.
The adjective form is cranial.
The adjective form for the pronoun they is their.
The Adjective form of Pathologist is Pathological.
The adjective form of concept is conceptual.The adjective form of conception is conceptional.