This noun denotes an inflated sense of self-importance, a puffing up with pride. The root imagery is literally of inflation or swelling. Paul includes it in his vice list when expressing concern about what he might find when he arrives in Corinth—quarreling, jealousy, outbursts of anger, and 'conceit.' The word appears only here in the New Testament but captures a recurring biblical concern: pride that puffs people up rather than building them up in love, the kind of arrogance that fragments Christian community.