the GNU version of the Collaborative International Dictionary of English
noun-plural. See 5th grain, n., 2 (b).
noun-plural. Pigeon's dung used in tanning. See Grainer. n., 1.
Word Usage
"The distribution of the grains is at first uniform, but it is found that the grains accumulate progressively in the lower layers until a limiting distribution is reached with reversible settling or expansion depending on whether the temperature is lowered or raised."