Refers to a detailed architectural or engineering plan, often a floor plan or technical drawing. The term is somewhat dated; modern usage often prefers 図面 (ずめん) or 設計図 (せっけいず).
I found the old house's floor plan.
設計図 specifically refers to a design plan or blueprint, often for construction or manufacturing. 絵図面 is broader and more old-fashioned.
Compound of 絵 (e, 'picture') + 図面 (zumen, 'drawing, plan'). The exact historical derivation is uncertain, but it likely emerged as a term for pictorial plans in architecture or engineering.