noun, noun or participle which takes 'suru', intransitive verb
Refers to a hen sitting on eggs to hatch them; used in poultry contexts.
この鶏は巣引きを始めた。
This hen has started setting.
Compound of 巣 (su, 'nest') and 引き (hiki, 'pulling'), from the verb 引く (hiku). The exact derivation is uncertain, but it likely refers to the hen drawing the nest around itself while brooding.