bʰewd-mn̥-
“bottom, ground beneath water”bottom, fund, found, foundation
Nominal of *bʰewdʰ- giving English bottom, Latin fundus > fund, found, foundation, profound.
Discussion
The PIE form *bʰewd-mn̥- (bottom, the ground beneath water) is a nominal derivative of the verbal root *bʰewd- (to strike, to push, to dig), formed with the result noun suffix *-mn̥- that produced words meaning "the thing produced by the action" — in this case, "that which has been pushed/dug down," hence bottom, foundation, ground.
The Germanic reflex is English bottom, from Old English botm, from Proto-Germanic *butmaz, continuing *bʰewd-mn̥- with the regular Germanic shift of PIE *bʰ > PGmc *b. The cognates are closely clustered: German Boden (ground, floor, soil), Dutch bodem (bottom, ground), Old Norse botn (bottom), and Swedish/Danish bund (bottom) all preserve the same form. The semantic range in Germanic spans physical bottom (bottom of a vessel, bottom of a river) to figurative foundation (rock bottom, the bottom line).
The Latin branch produced fundus (bottom, base, ground, estate), from an earlier *bʰund-os with a different suffix. Fundus is one of the most productive Latin roots in English borrowings: fundamental, foundation, fund (originally the bottom of a money chest, the base capital), profound (from the bottom, i.e. deep), and founder (to sink to the bottom, as a ship). The French-mediated forms fond (bottom, background — as in fond memories, from the base/ground of feeling) and fondue (literally "melted," from fondre, though this derives from a different Latin verb) are sometimes confused with fundus derivatives.
The semantic connection between "bottom" and "estate" in Latin fundus is culturally revealing. A fundus was a piece of ground, a landed estate — the physical bottom, the earth itself, conceived as the foundation of wealth. This is the direct source of English fund, funded, and financial funding: money imagined as a base or bottom from which returns grow.
Greek pythḗn (πυθμήν, "bottom, base of a vessel") provides the Hellenic reflex, with the expected Greek treatment of the labial: PIE *bʰ > Greek ph (Grassmann's Law may complicate the initial consonant in some forms). The Greek word appears primarily in technical contexts — the bottom of a cup, the base of a column — and did not develop the metaphorical extensions found in Latin and Germanic.
The Sanskrit cognate budhná- ("bottom, depth") preserves the root with characteristic Indo-Iranian voicing. The Vedic form appears in cosmological contexts, describing the bottom of the cosmic ocean and the foundation of the world-pillar.
The suffix *-mn̥- is the same instrumental/result suffix seen in *srew-mn̥- (stream, "that which flows") and other PIE formations. Its survival in both the Germanic (-m in bottom) and Latin (-nd- in fundus via a different morphological path) branches confirms its PIE antiquity.