1. [ noun ] the 16th letter of the Roman alphabet
Related terms: letter Roman_alphabet
2. [ noun ] (chemistry) a multivalent nonmetallic element of the nitrogen family that occurs commonly in inorganic phosphate rocks and as organic phosphates in all living cells; is highly reactive and occurs in several allotropic forms
Synonyms: phosphorus atomic_number_15
Related terms: chemical_element apatite
Similar spelling:   Pa