(American football) The second down in a series that has a maximum of four downs.

(geometry) A portion of a circle enclosed by two radii and an arc.

Alternative spelling of circular sector

A branch of information security applied to both theoretical and actual computer systems and networks.

(finance) The financial market for trading of securities that have already been issued in an initial private or public offering.

A person who is employed to provide security for people or property.

(engineering) A measure of a body's resistance to bending; second moment of area.

(engineering) A measure of a body's resistance to bending.

The voting system involving ballots available only at official polling places, prepared at public expense, containing the names of all candidates, and marked in secret at the polling places.

The process of raising doubt or coming to a different conclusion through further consideration; the doubts or new conclusion resulting from this process.