1. (Science: geology) round, water-worn, and loose gravel and pebbles, or a collection of roundish stones, such as are common on the seashore and elsewhere.
2. (Science: botany) Shingle oak, a kind of oak (quercus imbricaria) used in the western states for making shingles.
Origin: Prob. From Norw. Singl, singling, coarse gravel, small round stones.