The word 'stock' originates from the Old English 'stoc', meaning "tree trunk, post, or stake." This concrete sense of a solid, foundational wooden object provided a powerful metaphorical basis for expansion. From the idea of a trunk as the source from which a family line grows, it came to mean lineage or ancestry. In commerce, the concept evolved from the "trunk" or main fund of capital from which a business operates, leading to its financial meanings of investment shares and the total goods held for trade. The culinary sense of "stock" as a foundational broth derives from the same core idea of a base or foundation from which something (like a soup) is built.

This is a simplex word of Old English origin. The Old English form 'stoc' had a core meaning of "tree trunk, post, stake," which served as the foundational concept for its later semantic developments.