\Ro*tun"da\, n. [Cf. It. rotonda, F. rotonde; both fr.
L. rotundus round. See {Rotund}, a.] (Arch.)
A round building; especially, one that is round both on the
outside and inside, like the Pantheon at Rome. Less properly,
but very commonly, used for a large round room; as, the
rotunda of the Capitol at Washington.