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.

A hierarchy of values that all moral beings have, reflected in their choices. Most people's value systems differ. It's an individualistic concept. One's value system is molded by one's virtues or vices, and experiences.

A pushchair with detachable carrycot or car seat.

(anatomy) Part of the human brain involved in emotion, motivation, and emotional association with memory; includes amygdala, cingulate gyrus, fornicate gyrus, hippocampus, hypothalamus, mammillary body, nucleus accumbens, orbitofrontal cortex and parahippocampal gyrus.

A system of beliefs.

A group of related components that are part of a larger system.

(anatomy) A system of organs for the purpose of digesting food.

(anatomy) The skin, feathers and other outer coverings of an animal.

(taxonomy) A coherent system of taxonomic judgements on circumscription and placement of the considered taxa. A taxonomic system is restricted to a large but limited part of the living world.