ULTIMATE UX DICTIONARY
Index
They indicate something. The index connected with its meaning (not arbitrary) but unlike the icon, it’s not the object itself. As examples, we can say that smoke indicates fire, smiles indicate happiness, fresh coffee smell in the morning indicates that someone preparing breakfast. Even medical symptoms and measuring instruments are indexes, because they indicate something.
Gamification Technique: Social Leaderboard
A version of a relative leaderboard that shows only users from a user’s connected social network such as Facebook.
Signifier
an acoustic image (the ‘signifiant’, or signifier); literal meaning ex. red apple