Defn: A series of six notes, with a semitone between the third and fourth, the other intervals being whole tones.

HEXACID
Hex`ac"id, a. Etym: [Hex- + acid.] (Chem.)

Defn: Having six atoms or radicals capable of being replaced by acids; hexatomic; hexavalent; — said of bases; as, mannite is a hexacid base.

HEXACTINELLID
Hex*ac`ti*nel"lid, a. (Zoöl.)

Defn: Having six-rayed spicules; belonging to the Hexactinellinæ.

HEXACTINELLINE
Hex*ac`ti*nel"line, a. Etym: [From NL. Hexactinellinæ, fr. Gr.
(Zoöl.)

Defn: Belonging to the Hexactinellinæ, a group of sponges, having six-rayed siliceous spicules.

HEXACTINIA
Hex`ac*tin"i*a, n. pl. Etym: [NL. See Hex-, and Actinia.] (Zoöl.)

Defn: The Anthozoa.

HEXAD
Hex"ad, n. Etym: [L. hexas, hexadis, the number six, Gr. (chem.)