LENS n.
urfaces, either both curved, or one curved and the other plane, and commonly used, either singly or combined, in optical instruments, for changing the direction of rays of light, and thus magnifying objects, or otherwise modifying vision. In practice, the curved surfaces are usually spherical, though rarely cylindrical…
SPORADIC a.
Occuring singly, or apart from other things of the same kind, or in scattered instances; separate; single; as, a sporadic fireball; a sporadic case of disease; a sporadic example of a flower. Sporadic disease (Med.), a disease which occurs in single and scattered cases. See the Note under Endemic, a.…