Adjective

1. Preferred or liked above all others (unless qualified.)

   This is my second favourite occupation.

Noun

1. A person who enjoys special regard or favour.
2. A person who is preferred or trusted above all others.
3. A contestant or competitor thought most likely to win.

   You were my favourite to win the spelling competition.

Verb

2. To bookmark.
3. To add to one's list of favourites on a website that allows users to compile such lists.