YES!!! Because most adverbs in the English language end in '==ly'.
No, it cannot be a conjunction. Mostly is an adverb.
The adjective large has the adverb form "largely" (which means mostly).
adverb or adjective
Adverbs mostly, but don't always, have the suffix -ly on the end.The adverb of ample is amply.
The word sparkle is a noun or a verb. There is an adjective (sparkling) and an mostly unrecognized adverb form, which is "sparklingly."
Mostly is an adverb. It is used to describe the frequency, extent, or degree of an action or quality.
Necessary is not an adverb: it is most commonly used as an adjective.
The word entreatingly is an adverb. You can easily tell if a word is an adverb as they mostly end in the suffix -ly.
"largely" is an adverb that is used to describe to what extent something is true, accurate, or done.
winters are very cold
The correct spelling of the adverb is mostly (to a great extent, primarily).
The adverb is amply.Adjectives that end in -LE (mostly -able, ible, and simple, single) form the adverb by replacing the E with Y.(One, whole, drops the E and adds LY to make the adverb wholly.)