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.