Old English cild "fetus, infant, unborn or newly born person," from Proto-Germanic *kiltham (cf. Gothic kilþei "womb," inkilþo "pregnant;" Danish kuld "children of the same marriage;" Old Swedish kulder "litter;" Old English cildhama "womb," lit. "child-home"); no certain cognates outside Germanic. "App[arently] originally always used in relation to the mother as the 'fruit of the womb'" [Buck]. Also in late Old English, "a youth of gentle birth" (archaic, usually written childe). In 16c.-17c. especially "girl child."
The wider sense "young person before the onset of puberty" developed in late Old English. Phrase with child "pregnant" (late 12c.) retains the original sense. The sense extension from "infant" to "child" also is found in French enfant, Latin infans. Meaning "one's own child; offspring of parents" is from late 12c. (the Old English word was bearn; see bairn). Figurative use from late 14c. Most Indo-European languages use the same word for "a child" and "one's child," though there are exceptions (e.g. Latin liberi/pueri).
The difficulty with the plural began in Old English, where the nominative plural was at first cild, identical with the singular, then c.975 a plural form cildru (genitive cildra) arose, probably for clarity's sake, only to be re-pluraled late 12c. as children, which is thus a double plural. Middle English plural cildre survives in Lancashire dialect childer and in Childermas.
Child abuse is attested by 1963; child-molester from 1950. Child care is from 1915. Child's play, figurative of something easy, is in Chaucer (late 14c.).
child (chīld)
n.
A person between birth and puberty.
An unborn infant; a fetus.
An infant; a baby.
One who is childish or immature.
A son or daughter; an offspring.
This word has considerable latitude of meaning in Scripture. Thus Joseph is called a child at the time when he was probably about sixteen years of age (Gen. 37:3); and Benjamin is so called when he was above thirty years (44:20). Solomon called himself a little child when he came to the kingdom (1 Kings 3:7). The descendants of a man, however remote, are called his children; as, "the children of Edom," "the children of Moab," "the children of Israel." In the earliest times mothers did not wean their children till they were from thirty months to three years old; and the day on which they were weaned was kept as a festival day (Gen. 21:8; Ex. 2:7, 9; 1 Sam. 1:22-24; Matt. 21:16). At the age of five, children began to learn the arts and duties of life under the care of their fathers (Deut. 6:20-25; 11:19). To have a numerous family was regarded as a mark of divine favour (Gen. 11:30; 30:1; 1 Sam. 2:5; 2 Sam. 6:23; Ps. 127:3; 128:3). Figuratively the name is used for those who are ignorant or narrow-minded (Matt. 11:16; Luke 7:32; 1 Cor. 13:11). "When I was a child, I spake as a child." "Brethren, be not children in understanding" (1 Cor. 14:20). "That we henceforth be no more children, tossed to and fro" (Eph. 4:14). Children are also spoken of as representing simplicity and humility (Matt. 19:13-15; Mark 10:13-16; Luke 18:15-17). Believers are "children of light" (Luke 16:8; 1 Thess. 5:5) and "children of obedience" (1 Pet. 1:14).