An adverb modifies a word, phrase, or sentence. It tells us more about them and changes the meaning slightly. Often we say it tells us how something happens:
They are waiting for the metro.
They are waiting patiently for the metro.
In this example above, the adverb tell us how the people are waiting for the metro.
Regular & Irregular Adverbs in English
The difference between regular adverbs and irregular adverbs, has mainly to do with their formation (that is, with way adverbs are made).
The most common way to make adverbs is by adding –ly to an adjective. Because this type of adverb formation applies in almost 90% of cases all adverbs ending in –ly are known as regular adverbs in as much as they follow a basic rule.
Here we have a list of adjectives which have been turned into adverbs by simply adding –ly:
slow > slowly
loud > loudly
great > greatly
perfect > perfectly
sincere > sincerely
However there are cases where we cannot just add -ly to an adjective. We need to make some changes to the spelling. This happens when:
1. the adjective ends in -y in which case the –y changes into –i before –ly is added
speedy > speedily
angry > angrily
ready > readily
2. the adjective ends in -able, -ible, or -le in which case the –e changes into –y
gentle > gently
humble > humbly
probable > probably
3. the adjective ends in -ic in which case simply add –ally
economic > economically
basic > basically
ergonomic > ergonomically
Exception: public > publicly, and not * publically.
Useful Links
Adverbs in English Grammar – an overview of adverbs in general
Irregular Adverbs in English Grammar – a look at adverbs which are made in an irregular way