In`stan*ta"ne*ous (?), a. [Cf. F.
1. Done or occurring in an instant, or
without any perceptible duration of time; as, the passage of
electricity appears to be instantaneous.
His reason saw
With instantaneous view, the truth of things.
2. At or during a given instant; as,
instantaneous acceleration, velocity, etc.
Instantaneous center of rotation
(Kinematics), in a plane or in a plane figure which has
motions both of translation and of rotation in the plane, is the
point which for the instant is at rest. -- Instantaneous
axis of rotation (Kinematics), in a body which
has motions both of translation and rotation, is a line, which is
supposed to be rigidly united with the body, and which for the
instant is at rest. The motion of the body is for the instant simply
that of rotation about the instantaneous axis.
-- In`stan*ta"ne*ous*ly, adv. --