"Looking For More" is often used by a player character in a group with less than 5 members who wants to fill out the group, usually to pursue a quest.
Usually shortened in chat to LFM. Sometimes accompanied with specific classes or levels desired.
There is a variant acronym known as LFRM, which is "Looking for Raid Members".
Also a sub-feature of the in-game Dungeon Finder (LFG) feature.