An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1a) A thing added to something else in order to complete, reinforce, or extend it.
1b) A separation section added to a book, document, etc., to supply additional or later information, or the like.
2a) To complete, add to, or extend by a supplement.
2b) To form a supplement or addition to.

From L. supplementum "that which fills up, that with which anything is made full or whole, something added to supply a deficiency," from supplere "to fill up, complete," from → sub- "up from below" + plere "to fill;" cognate with Pers. por, as below.

Âporidan, from prefix â- + por "full;" Mid.Pers. purr; O.Pers. paru- "much, many;" Av. parav-, pauru-, pouru-, from par- "to fill;" PIE *pelu- "full," from *pel- "to be full;" cf. Skt. puru-; Gk. polus; P.Gmc. *fullaz (O.H.G. fol, Ger. voll, Goth. full, O.E. full).

Completing something or added as a supplement.

→ supplement; → -ary.

The angle that when added to a given angle makes 180°. → complementary angle.

→ supplementary; → angle.