シャ, やしろ, こそ
company, firm, office, association, shrine
JLPT4 G2 S7 F21
As per 土# (pile of earth) + 示 altar/the supernatural → crowd thronging an (earthen) altar → *group of like-minded people*; (Shinto) *shrine*. Abbreviation for *company* is a Meiji-era coinage representing an extended sense of the term (group formed for a specific purpose).
[Full Kanji Etymology List]