twinning

American  

[twin-ing] / ˈtwɪn ɪŋ /

noun

1. the bearing of two children at one birth.

2. the coupling of two persons or things; union.

3. Crystallography. the union of crystals to form a twin.

4. an act or instance of matching or resembling someone or something in a specific way, and the acknowledgment of this resemblance (often used attributively): I love those twinning outfits.

   accidental twinning;

   I love those twinning outfits.

   Look at their twinning duckfaces.

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Etymology

Origin of twinning

First recorded in 1565–75; twin ¹ + -ing ¹