the.com/string vest

means A knitted, open-mesh sleeveless undershirt with a loose lattice of holes, worn mainly for warmth-without-bulk and, notoriously, as a naff fashion statement.

from The garment itself has roots in Scandinavian and military cold-weather underwear, where the open-knit construction traps warm air in its gaps — the holes aren't a flaw, they're the insulation. 'String' simply names the thin cord-like yarn used in the knit; 'vest' is the long-standing British word for an undershirt, from Latin 'vestis' meaning garment or clothing. No elaborate tale needed here — the name is just plainly descriptive, even if the garment's reputation (think 1970s terrace fashion) became a joke all its own.