(botany) The structure comprising the roots of a plant.

Alternative letter-case form of Solar System; the Sun and all the objects in orbit around it.

Any collection of heavenly bodies including a star or binary star, and any lighter stars, brown dwarfs, planets, and other objects in orbit.

(US, alternative in Canada) A system, policy or understanding based on trust in the honesty, honor, or integrity of others.

Alternative spelling of file system

plural of systemic circulation

(biology) A system for characterizing the sex of animals, such as butterflies and Komodo dragons, in which males have two of the same kind of sex cell (ZZ) and females have two distinct sex cells (ZW).

(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).

plural of system operator

(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).