n.
Pronunciation: h ī - ˌ dräk-s ē - ' a-p ə - ˌ t ī t
Variant: or hy · drox · yl · ap · a · tite \ -s ə - ' la-p ə - ˌ t ī t \
Function: noun
Date: 1912
: a complex phosphate of calcium Ca 5 (PO 4 ) 3 OH that occurs as a mineral and is the chief structural element of vertebrate bone