An archaic exclamation or minced oath, variants of which appear in Early Modern English texts.
From 'God's' combined with what may be a corruption of 'eyelid' or another body part, following the pattern of bodily minced oaths.
The invention of obscure oaths like 'gadslid' reveals how constrained Early Modern speakers felt about blasphemy—they literally created silly alternatives just to complain safely.
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