Хэрэглээ – adjective эсвэл adverb

Adjectives are used to modify nouns. For example:

The dog is loud. What is the dog like? He is loud.

Adverbs are used to modify verbs, adjectives or other adverbs. For example:

The dog barks loudly. How does the dog bark? He barks loudly.

In general: adjective + -ly

adjective	adverb
slow	slowly

Exceptions in spelling

exception	example
silent e is dropped in true, due, whole	true → truly
y becomes i	happy → happily
le after a consonant is dropped	sensible → sensibly
after ll only add y	full → fully

Adjectives ending in -ic: adjective + -ally (exception: public-publicly)

adjective	adverb
fantastic	fantastically

Adjectives ending in -ly: use "in a ... way / manner" or another adverb with similar meaning

adjective	adverb
friendly	in a friendly way in a friendly manner
likely	probably

Exceptions

adjective	adverb (meaning)	adverb (meaning)
good	well
difficult	with difficulty
public	publicly
deep	deep (place)	deeply (feeling)
direct	direct	directly (=soon)
hard	hard	hardly (=seldom)
high	high (place)	highly (figurative)
late	late	lately (=recently)
most	most	mostly (=usually)
near	near	nearly (=almost)
pretty	pretty (=rather)	prettily
short	short	shortly (=soon)
The following adjectives are also used as adverbs (without modification):	daily, enough, early, far, fast, hourly, little, long, low, monthly, much, straight, weekly, yearly, ...

Comparison

Comparison (-er/-est)

	Comparative ending in -er	Superlative ending in -est
one-syllable adverbs (hard)	harder	hardest
adverbs with the same form as adjectives (early)	earlier	earliest

Comparison (more / most)

	Comparative formed with more	Superlative formed with most
adverbs ending in -ly (happily)	more happily	most happily

Irregular comparisons

positive form	comparative	superlative
well	better	best
badly	worse	worst
ill	worse	worst
little	less	least
much	more	most
far (place + time)	further	furthest
far (place)	farther	farthest
late (time)	later	latest