The Sun and all the heavenly bodies that orbit around it, including the eight planets, their moons, the asteroids, and comets.

An informal method of communication used to pass information to US citizens during emergencies.

Any data processing system, either manual or computerized. / Any telecommunications system whose primary function is to transmit and/or display data.

(anatomy) The system of osteons in compact bone

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

A communication system in which multiple users share a common channel in a way that can lead to conflicts.

A system of beliefs.

(physiology) The parts of an animal body comprising the heart, blood vessels (arteries, veins, and capillaries), and blood, which circulate the blood around the body.

(medicine) A blood group system, the second most important after the ABO system, and important in human blood transfusion, whereby blood types are classified according to the presence ("positive") or absence ("negative") of potentially over 50 antigens, of which the most commonly referenced is RhD.

In Latin, the three perfect tenses: perfect, future perfect, and pluperfect or past perfect, as contrasted with the present system: present, future, and imperfect. A verb in the perfect system indicates an action that has completed.