Noun
A
barbiturate
C
<
sub
>
12
sub
>
H
<
sub
>
18
sub
>
N
<
sub
>
2
sub
>
O
<
sub
>
3
sub
>
that
is
used
chiefly
in
the
form
of
its
bitter
hygroscopic
sodium
salt
as
a
hypnotic
and
sedative
.