Rivulet is a Modern English word meaning 'small stream', from Latin rivus ('stream') plus the diminutive suffix -ulus, via Italian rivuletto and Middle French rivolet. In current use it is a noun meaning "a small stream or brook, often a minor tributary of a river". That sense is explained by the older material without requiring a speculative semantic step: the inherited or borrowed base supplies the field of meaning, while the English formation fixes its modern role. The surface form is compositional: its joined elements remain visible in the modern word. A diminutive element is part of the history, marking a smaller or derived form. The word's history is thus visible in its construction: the components remain interpretable even after the whole expression has settled into a conventional English meaning.