Question: words which are both adjectives and adverbs?
Answer: Adjectives ending in -ly. Note that the following words can be used only as adjectives and not as adverbs: beastly, costly, cowardly, deadly, friendly, likely, brotherly, kingly, leisurely, lovely, lively, womanly, princely, scholarly, silly, ugly and unlikely. ...  Fast. ...  Half. ...  Straight. ...  Just. ...  Late. ...  Low. ...  Most.