A Grammatical Dictionary of Botanical Latin

Pentad (Eng.noun), a pentad, a group of five: pentas,-adis (s.f.III), abl.sg. pentade, nom.& acc. pl. pentades, gen.pl. pentadum, dat. & abl.pl. pentadibus; also pemtas,-adis (s.f.III), abl.sg. pemptade [> Gk. pente, five; cf. pemptos,-E,-on Gk. adj. (pente) the fifth, oneself with four others; cf. to pempton meros, a fifth (part)]; see monad, dyad, tetrad, triad;

NOTE: possibly also pentadum,-i (s.n.II), abl.sg. pentado, following Stearn (1983) for ‘tetrad,’ q.v.

- Stirpium historiae pemptades sex sive libri XXX (1583) (six pemptads [i.e. pentads, or groups of five] or 30 books on a history of plants).

Note: six pentads = 30 (six groups of five); by the Flemish physician and botanist Rembert Dodoens, (Latin:) Rembertus Dodonaeus, (original name:) Rembert Van Joenckema (June 29, 1516/17, Mechelen, Spanish Netherlands [now in Belgium] — March 10, 1585, Leiden, Neth.). The work is considered one of the foremost botanical publications of the late 16th century.