diagonal
adj.
1540s (implied in diagonally), from Middle French diagonal, from Latin diagonalis, from diagonus "slanting line," from Greek diagonios "from angle to angle," from dia- "across" (see dia-) + gonia "angle" (see -gon). As a noun, from 1570s.
〔李〕[dia-=across 对面的；gon=angle 角；-al a.=being⇒“being across angles 横跨对面角的”→] a. ①connecting two corners that are not next to each other 对角的