The quality of being imprudent.

(organic chemistry) Describing any organic compound containing a carbon to erbium bond.

The central region of Saudi Arabia.

A filter of trapezoidal shape specified by four corner frequencies, f1 through f4. The filter rejects below f1 and above f4, is linear from f1 to f2 and from f3 to f4, and is flat from f2 to f3.