Full combo (or FC for short) is a term used to describe a player obtaining the maximum possible combo on a beatmap. Full combos are scored by passing a beatmap with no misses, sliderbreaks, or dropped slider ends.
Scores that lost combo only via dropped slider ends are widely considered by the community to be full combos. This differs from the game client and website's display.
The top score is a full combo, and the bottom score is a broken combo.
Because the score of an individual object in osu! and osu!catch heavily depends on combo multiplier and is virtually unbounded, full combos typically award the most score in these game modes.