The system of units developed in France in the 1790s and now used worldwide.

A system of measurement in use in the United Kingdom and other Commonwealth countries, now mostly superseded by the metric system; similar to the system currently used in the United States; consisting of units such as the inch, the mile and the pound (of weight).

plural of sealed system

Any device with inner workings obscured.

(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.

(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.

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.

In Latin, the three simple tenses: present, future, and imperfect, as contrasted with the perfect system, the three perfect tenses: perfect, future perfect, and pluperfect. Verbs in the present system tend to indicate an action that has not completed.

plural of travel system

plural of immune system