c. 1200, "numeral;" mid-13c., "visible appearance of a person;" late 14c., "visible and tangible form of anything," from Old French figure "shape, body; form of a word; figure of speech; symbol, allegory" (10c), from Latin figura "a shape, form, figure; quality, kind, style; figure of speech," in Late Latin "a sketch, drawing," from PIE root *dheigh- "to form, build."
Philosophical and scientific senses are from use of Latin figura to translate Greek skhema. Meaning "lines forming a shape" is from mid-14c. From mid-14c. as "human body as represented by art;" late 15c. as "a body, the human form as a whole." The rhetorical use of figure, "peculiar use of words giving meaning different from usual," dates to late 14c.; hence figure of speech (by 1704). Figure-skating is from 1835. Figure eight as a shape was originally figure of eight (c. 1600). From late 14c. as "a cut or diagram inserted in text."