the flat part of a knife, tool or machine, which has a sharp edge or edges for cutting 刀身；刀片；刀刃 
Extra Examplessee also razor blade, switchbladeThe machine comes with a plastic guard over the blade to protect the operator. 机器在刀片上带有塑料保护罩，以保护操作员。 Knife blades are generally made of stainless steel. 刀刃通常是用不锈钢制成的。 The prisoner used a hacksaw blade to cut through the bars. 囚犯用钢锯锯切掉了酒吧。 He swung the blade with all his strength. 他使出全身的力气挥舞刀。 The swordsmen weaved and dodged as their blades clashed over and over again. 剑客们在剑锋的反复撞击声中腾挪躲闪。
Oxford Collocations Dictionaryadjective- sharp
- blunt
- dull
- …
- sharpen
- draw
- sheathe
- …
one of the flat parts that turn around in an engine or on a helicopter （机器上旋转的）叶片；桨叶 
the blades of a propeller 螺旋桨叶 rotor blades on a helicopter 直升机的旋翼
Oxford Collocations Dictionaryadjective- sharp
- blunt
- dull
- …
- sharpen
- draw
- sheathe
- …
the flat wide part of an oar (= one of the long straight pieces of wood that are used to row a boat) that goes in the water （船桨的）桨叶，桨身 a single flat leaf of grass （草的）叶片 
Not a blade of grass stirred. 没有草叶搅动。
the flat metal part on the bottom of an ice skate （溜冰鞋的）冰刀 
see also shoulder blade
Word OriginOld English blæd ‘leaf of a plant’ (also in sense (2)), of Germanic origin; related to Dutch blad and German Blatt.