Green’s Dictionary of Slang

kinchin n.

also kinch, kinchen, kinshin, little kinchin
[Ger. Kindchen, MDu. kindeken, a little child; NB ‘Sl. Terms & the Gypsy Tongue’ in Baily’s Mag. Nov. 1871 suggests origin in Hindi chinchinana, to squeak]
(UK Und.)

1. [mid-16C–1900s] a (small) child.

2. [mid-18C–mid-19C] a young woman, a little girl; thus attrib.

In compounds

kinchin co (n.) (also kinchin(g) co, kitching co, kynchen-co, kynchin-co) [co = cove n. (1)]

[mid-16C–early 19C] (UK Und.) a child who has been brought up to thieving as a profession.

kinchin cove (n.) (also kinchen cove) [cove n. (1)] (UK Und.)

1. [late 17C–mid-19C] a little man.

2. [late 17C–mid-19C] a child brought up as a thief.

3. [late 18C–mid-19C] a man who steals children for gypsies, beggars, etc.

kinchin lay (n.) (also kinchen lay) [lay n.3 (1)] [mid-19C–1900s]

1. street stealing from children.

2. in fig. use, i.e. devoting oneself to the topic of children.

kinchin mort (n.) (also kinchen-mort, kinching mort, king’s mot(t), kitchen mort, kitchin mort) [mort n. (1)] [mid-16C–mid-19C] (UK Und.)

1. a beggar’s child, or any child carried by a beggar in order to excite pity.

2. a young, virgin girl, destined to be a prostitute or beggar’s companion.

kinchin prig (n.)

[mid-19C] (UK Und.) a young thief.