From Old English meaning “an assertion of fact from firsthand knowledge” and also “someone who testifies.” Original definition is “having a quality of knowledge, understanding, or wit,” (wit (n.) + -ness). Use by fourteenth-century Christians is a literal translation of the Greek martys, meaning martyr.
From witness (n.), this carried the meaning of “bear testimony.” Regarding wills and other legal documents, “affix one’s signature to establish identity” is from early fourteenth century. Meaning “to observe, see, or know firsthand through one’s senses (e.g., seeing, hearing)” is from the 1580s.
Sentences using WITNESS: