(biology) The system that determines the sex of humans, most other mammals, some insects (Drosophila), and some plants (Ginkgo), in which females have two of the same kind of sex cell (XX) and males have two distinct sex cells (XY).

(biology) The system that determines the sex of offspring among grasshoppers, crickets, cockroaches, and some other insects, in which females have two sex cells (XX) and males have only one sex cell (X0, or simply X; the 0 signifies the lack of another X).

plural of system tray

(computing, graphical user interface) The portion of the taskbar that displays the system time and icons for running processes, which can often launch menus for those processes.

plural of lymphatic system

plural of block system

A fire alarm system.

(aviation, travel) Airline baggage allowance that restricts passengers to a specific number of bags, rather than a specific weight.

A manner of responding to challenges with quick thinking and improvisation.

A convention whereby Esperanto’s circumflex accents (ĉ, ĝ, ĥ, ĵ, ŝ, ŭ) are replaced by an x after the non-diacriticked letter (cx, gx, hx, jx, sx, ux), for convenience of typing.