Pianissimo or pp
DEFINITION
(usually) very gently; i.e., perform very softly, even softer than piano. This convention can be extended; the more ps that are written, the softer the composer wants the musician to play or sing, thus ppp (pianississimo) would be softer than pp. Dynamics in a piece should be interpreted relative to the other dynamics in the same piece. For example, pp should be executed as softly as possible, but if ppp is found later in the piece, pp should be markedly louder than ppp. More than three ps (ppp) or three fs (fff) are uncommon.