Roughly
I would say SMOOTHLY, but someone else might come up with another idea.
No; it's an adverb "She smoothly walked." (smoothly is describing how she walked, the verb) "It was smoothly polished." (smoothly describes polished, the adjective)
yes
No. It is an adverb.
"Smoothly" functions as an adverb. It is used to modify verbs, adjectives, or other adverbs, indicating how an action is performed.
'smooth;y' is and Adverb. In the English language words ending in '---ly' are adverbs.
opposite is an adjective
The opposite of the adverb bitterly is sweetly.The word sweetly is also an adverb.
smoothly
Effortlessly or smoothly.
I hope that this program will be run smoothly.
The opposite of the adverb firmly (securely) is loosely.*When used to mean forcefully or determinedly (e.g. firmly stated), the opposite could be gently, weakly, or waveringly.