ALLANTOIDEA
Al`lan*toid"e*a, n. pl. Etym: [NL.] (Zoöl.)

Defn: The division of Vertebrata in which the embryo develops an allantois. It includes reptiles, birds, and mammals.

ALLANTOIN
Al*lan"to*in, n. (Chem.)

Defn: A crystalline, transparent, colorless substance found in the allantoic liquid of the fetal calf; — formerly called allantoic acid and amniotic acid.

ALLANTOIS; ALLANTOID
Al*lan"to*is, Al*lan"toid, } n.. (Anat.)

Defn: A membranous appendage of the embryos of mammals, birds, and reptiles, — in mammals serving to connect the fetus with the parent; the urinary vesicle.

ALLATRATE
Al"la*trate, v. i. Etym: [L. allatrare. See Latrate.]

Defn: To bark as a dog. [Obs.] Stubbes.

ALLAY Al*lay", v. t. [imp. & p. p. Allayed; p. pr. & vb. n. Allaying.] Etym: [OE. alaien, aleggen, to lay down, put down, humble, put an end to, AS. alecgan; a- (cf. Goth. us-, G. er-, orig. meaning out) + lecgan to lay; but confused with old forms of allege, alloy, alegge. See Lay.]

1. To make quiet or put at rest; to pacify or appease; to quell; to calm; as, to allay popular excitement; to allay the tumult of the passions.