means A person or entity that owns one or more shares of stock in a company, giving them a partial ownership stake and a claim on its profits.

from A transparent compound of "share" + "holder" — quite literally one who holds shares. "Share" descends from Old English "scearu," meaning a division, cutting, or portion (a cousin of "shear" and "share" the plow-blade — both about cutting things into parts). "Holder" is simply one who holds, from Old English "healdan." The financial sense of "share" as a divided unit of company ownership took root as joint-stock companies spread, and "shareholder" followed naturally to name the people clutching those slices.