1.Properly, the leaf, or flat part of the leaf, of any plant, especially of gramineous plants. The term is sometimes applied to the spire of grasses. "The crimson dulse... with its waving blade." "First the blade, then ear, after that the full corn in the ear."
2.The cutting part of an instrument; as, the blade of a knife or a sword.
3.The broad part of an oar; also, one of the projecting arms of a screw propeller.
4.The scapula or shoulder blade.
5.pl. (Arch.) The principal rafters of a roof.
6.pl. (Com.) The four large shell plates on the sides, and the five large ones of the middle, of the carapace of the sea turtle, which yield the best tortoise shell.
7.A sharp-witted, dashing, wild, or reckless, fellow; a word of somewhat indefinite meaning. "He saw a turnkey in a trice Fetter a troublesome blade."
8.The flat part of the tongue immediately behind the tip, or point. ""Lower blade" implies, of course, the lower instead of the upper surface of the tongue."
...