تَجْوِيفٌ

The making [a thing] hollow, or empty in the middle. (KL, PS.) You say, جوّفهُ, verbal noun تَجْوِيفٌ, [He made it hollow; hollowed it out;] he made it to have a جَوْف. (Msb.) And of a thing that is مُجَوَّف, (S, K,) i. e. أجْوَف, (S,) you say, فِيهِ تَجْوِيفٌ [In it is a hollowing out; meaning a hollow, in which sense تجويف has a plural, namely, تَجَاوِيفُ]. (S, K.)

See also 1.