sooth \sooth\,
noun:
1. truth, reality, or fact.
adjective:
1. true or real.
In sooth, I know not why I am so sad.
-- William Shakespeare, "The Merchant of Venice," 1600
But in the young man's heart there was no answering gladness, though in very sooth she was an exceeding handsome maid.
-- Samuel Rutherford Crockett, "The Lilac Sunbonnet: A Love Story," 1895
Sooth derives from the Old English soư meaning "truth, justice; reality." It shares this root with the word soothe, as reflected in soothe's earliest sense, "to verify."
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