What is to grow or become thin; -- used with some adverbs, as out, away, etc.; as, geological strata thin out, i. e., gradually diminish in thickness until they disappear called?

thin — To grow or become thin; -- used with some adverbs, as out, away, etc.; as, geological strata thin out, i. e., gradually diminish in thickness until they disappear. (Webster's 1913.)

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