A characteristic movement of the primate thumb, in which the pad of the thumb can be placed in contact with the pads of the fingers of the same hand.
The position of two celestial bodies when their celestial longitude differs by 180°, especially a configuration in which Earth lies on a straight line between the Sun and a superior planet or the Moon. Planets in this position rise as the Sun sets and are visible all night long, reaching their highest point in the sky at midnight; the Moon in this position is full. Compare conjunction. See more at elongation.