family

1. a kinship unit consisting of a group of individuals united by blood or by marital, adoptive, or other intimate ties. Although the family is the fundamental social unit of most human societies, its form and structure vary widely. See biological family; extended family; nuclear family; permeable family; stepfamily.

2. in biological taxonomy, a main subdivision of an order, consisting of a group of similar, related genera (see genus).

3. a collection of mathematically or statistically related entities. For example, a set of statistical tests conducted when there are more than two groups for an independent variable within an analysis of variance constitutes a family of tests. See also family-wise alpha level; family-wise error rate. —familial adj.

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Psychology term of the day

January 26th 2025

congenital oculomotor apraxia

a condition, present at birth, in which a child is unable to fixate objects normally (see oculomotor apraxia). It is characterized by the absence of saccades and smooth-pursuit eye movements in the horizontal plane, but vertical eye movements are preserved: Children with this condition are often mistakenly thought to be blind. Between the ages of 4 and 6 months, they develop thrusting, horizontal head movements, sometimes blinking prominently or rubbing their eyelids when they attempt to change fixation. The cause of congenital oculomotor apraxia is unknown, but there is usually an improvement with age.