Reconstruction:Proto-Slavic/sedmica

Etymology
From.

Compare 🇨🇬,, 🇨🇬, 🇨🇬, , 🇨🇬 and 🇨🇬.

Meaning "week" is calque of 🇨🇬 or 🇨🇬. See also 🇨🇬, 🇨🇬, 🇨🇬, 🇨🇬.

Per Melnychuk, 🇨🇬 is borrowing from Church Slavonic.

Noun

 * 1) septuple set or order of seven

Descendants

 * East Slavic:
 * South Slavic:
 * Church Slavonic
 * West Slavic:
 * South Slavic:
 * Church Slavonic
 * West Slavic:
 * West Slavic:
 * West Slavic:
 * West Slavic:
 * West Slavic:
 * West Slavic:
 * West Slavic:
 * West Slavic: