Hyponitrous
(Hy`po*ni"trous) a. [Pref. hypo- + nitrous.] (Chem.) Containing or derived from nitrogen
having a lower valence than in nitrous compounds.
Hyponitrous acid (Chem.),
an unstable nitrogen acid, NOH, whose salts are produced by reduction
of the nitrates, although the acid itself is not isolated in the free state except as a solution in water; —
called also nitrosylic acid.
Hypopharynx
(||Hy`po*phar"ynx) n. [NL. See Hypo-, and Pharynx.] (Zoöl.) An appendage or fold on
the lower side of the pharynx, in certain insects.
Hypophosphate
(Hy`po*phos"phate) n. (Chem.) A salt of hypophosphoric acid.
Hypophosphite
(Hy`po*phos"phite) n. (Chem.) A salt of hypophosphorous acid.
Hypophosphoric
(Hy`po*phos*phor"ic) a. [Pref. hypo- + phosphoric.] (Chem.) Pertaining to, or derived
from, or containing, phosphorus in a lower state of oxidation than in phosphoric compounds; as, hypophosphoric
acid.
Hypophosphoric acid (Chem.),
an acid, P2H4O6, produced by the slow oxidation of moist phosphorus,
and isolated only as a solution in water. It is regarded as a condensation product of one molecule of
phosphoric acid with one of phosphorous acid, by partial dehydration.
Hypophosphorous
(Hy`po*phos"phor*ous) a. [Pref. hypo- + phosphorous.] (Chem.) Pertaining to,
or containing, phosphorus in a lower state of oxidation than in phosphoric compounds; as, hypophosphorous
acid.
Hypophosphorous acid (Chem.) , an acid, H3PO2, whose salts are produced by the action of barium
hygrate on phosphorus. It may be obtained from its water solution, by exaporation and freezing, as a
white crystalline substance. It is a powerful reducing agent.
Hypophyllous
(Hy*poph"yl*lous) a. [Pref. hypo- + Gr. leaf.] (Bot.) Being or growing on the under
side of a leaf, as the fruit dots of ferns.
Hypophysial
(Hy`po*phys"i*al) a. (Anat.) Of or pertaining to the hypophysis; pituitary.
Hypophysis
(||Hy*poph"y*sis) n. [NL., fr. Gr. under + nature, origin.]
1. (Anat.) See Pituitary body, under Pituitary.
2. (Med.) Cataract.
Hypoplastron
(Hy`po*plas"tron) n.; pl. Hypoplastra [Pref. hypo- + plastron.] (Anat.) The third lateral
plate in the plastron of turtles; — called also hyposternum.
Hypoptilum
(||Hy*pop"ti*lum) n.; pl. L. Hypoptila E. Hypoptilums [NL., fr. Gr. "ypo` beneath + down.]
(Zoöl.) An accessory plume arising from the posterior side of the stem of the contour feathers of many
birds; — called also aftershaft. See Illust. of Feather.
Hyporadius
(||Hy`po*ra"di*us) n.; pl. Hyporadii [Pref. hypo- + radius.] (Zoöl.) One of the barbs of
the hypoptilum, or aftershaft of a feather. See Feather.
Hyporhachis
(||Hy`po*rha"chis) n.; pl. Hyporhachides [NL., fr. Gr. "ypo` beneath + spine.] (Zoöl.)
The stem of an aftershaft or hypoptilum. [Written also hyporachis.]
Hyposkeletal
(Hy`po*skel"e*tal) a. [Pref. hypo- + skeletal.] (Anat.) Beneath the endoskeleton; hypaxial; as,
the hyposkeletal muscles; — opposed to episkeletal.