one-tub washing machine; single-tub washer
Refers to a washing machine with a single tub for both washing and spin-drying, as opposed to a two-tub (二槽式) model.
A one-tub washing machine doesn't take up much space, so it's suitable for living alone.
全自動洗濯機 is a fully automatic washing machine that handles washing, rinsing, and spinning in one tub, often synonymous with 一槽式 in modern usage.
Compound of 一 (one), 槽 (tub), and 式 (type/style). The term is straightforward and transparent.