Entry 1 sense Webster, 1913 Sinking · Sink·ing · IPA /ˈsɪŋkɪŋ/ 01 a. & n. a. & n. from Sink. 1. a. & n. from Sink. See: Sink Phrases & compounds Sinking fund — See under Fund. Sinking head — a riser from which the mold is fed as the casting shrinks. See Riser, n., 4. Sinking pump — a pump which can be lowered in a well or a mine shaft as the level of the water sinks.