From Wiktionary




  1. Adding -ly to the end of a noun turns the word into an adjective thus adding further information about the word and the meaning you are giving it. The adjectives now have the extra meaning of "like (the noun), as in something that is characteristic of (the noun)".
    If you say "He has manly facial features" you are saying that his facial features are typical facial features for a man.
  2. Adding the suffix-ly to the end of an adjective turns the word into an adverb. The meaning of the word does not change, and still conveys the same idea. But it is a shorter and, sometimes, more elegant way of saying or writing it.
    You can say, "Those are his usual clothes" or "That is how he usually dresses".
  3. However, this tiny two letter suffix is versatile because it can also be used to change the meaning, most often when it is applied to verbs.
    "Likely" ("it looks likely to rain") does not mean the same thing as when "like" is used here ("It looks more like drizzle than rain"). So, just through adding two letters to the end of a word, you can convey two totally different meanings.