zenith

‘z1i-n10. the pent directly above the observer’s hod; the vertical point of the hevens at any place; the vertex: as, the blue *zenzth; to dwindle in the *zenzth: the oppos it of nadir. astronomical zenith, the point at which a plum geocentric zenith, the point at which a line drawn from the center of the earth and pa ing thru the observer would, of produced upward, touch or pierce the celestial sfere. contrast astronomical zenith. plumb-line zenith, same meaning as astronomical zenith. ¥ | DICTIONARY OF AVIATION 267