scale

This word actually comes from three separate sources that collided in English. One is Latin scāla, 'staircase' or 'ladder', tied to scandō, 'to climb' (the same root behind ascend and descend). Another is Old French escale, from a Germanic word skala meaning 'shell' or 'husk', related to Old English sċealu. The third is Old Norse skál, 'bowl', from a different Germanic root.

Because these three words sounded alike once they reached English, they merged under a single spelling even though their meanings — climbing, shelling, and weighing — never truly touched.

The shell sense is a doublet of shale, which comes from the same Old English word sċealu. The bowl sense is cognate with Danish skål, 'bowl, cup', and German Schale.