A sinus may be rounded, as in the leaf of the white oak, or acute, as
in that of the red maple.
Pallial sinus. (Zoöl.) See under Pallial. -- Sinus venosus (?). [L.,
venous dilatation.] (Anat.) (a) The main part of the cavity of the
right auricle of the heart in the higher vertebrates. (b) In the lower
vertebrates, a distinct chamber of the heart formed by the union of the
large systematic veins and opening into the auricle.
Si"nus*oid (?), n. [Sinus + - oid.] (Geom.) The curve whose ordinates
are proportional to the sines of the abscissas, the equation of the
curve being y = a sin x. It is also called the curve of sines.
Si`nus*oid"al (?), a. (Geom.) Of or pertaining to a sinusoid; like a
sinusoid.
Sio"goon (?), n. See Shogun.
Sio*goon"ate (?), n. See Shogunate.
Sioux (?), n. sing. & pl. (Ethnol.) See Dakotas.
Sip (sp), v. t. [imp. & p. p. Sipped (spt); p. pr. & vb. n. Sipping.]
[OE. sippen; akin to OD. sippen, and AS. span to sip, suck up, drink.
See Sup, v. t.] 1. To drink or imbibe in small quantities; especially,
to take in with the lips in small quantities, as a liquid; as, to sip
tea. "Every herb that sips the dew." Milton.
2. To draw into the mouth; to suck up; as, a bee sips nectar from the
flowers.