1. A submersible warship usually armed with torpedoes
   "The sub silently patrolled enemy waters";
   - submarine, pigboat [informal]
    
2. [N. Amer, informal] A large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States
   "He ordered a classic Italian sub with all the toppings";
   - bomber [US, informal], grinder [US, informal], hero [N. Amer], hero sandwich [N. Amer], hoagie [N. Amer], hoagy [N. Amer], Cuban sandwich [N. Amer], Italian sandwich [N. Amer], poor boy [N. Amer], submarine [N. Amer], submarine sandwich [N. Amer], torpedo [US], wedge [US, informal], zep [N. Amer]

1. Put in the place of another; switch seemingly equivalent items
   "She subbed margarine for butter in the recipe";
   - substitute, replace, interchange, exchange
    
2. Be a substitute
   "The young teacher had to sub for the sick colleague";
   - substitute, stand in, fill in
    
3. Act or speak as a replacement (for someone or something)
   "He often subs for absent teachers";
   - substitute, deputize, deputise [Brit], step in

1. Under, lower, below, secondary, inferior
   - under-

Derived forms: subs, subbing, subbed

Type of: alter, change, exchange, interchange, modify, replace, sandwich, sarnie [Brit, informal], submersible, submersible warship, supercede [non-standard], supersede, supervene upon, supplant

Encyclopedia: Sub