tube tube /tˈjuːb/

noun

1. () Conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects, liquids or gases  ( tubing , tube )
   conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects, liquids or gases
     She squeezed the toothpaste out of the tube.
   She squeezed the toothpaste out of the tube.
   
   
2. () Electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope  ( electron tube , thermionic tube , thermionic vacuum tube , thermionic valve , tube , vacuum tube )
   electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope
     The scientist inserted a sample into the test tube.
   The scientist inserted a sample into the test tube.
   
   
3. () A hollow cylindrical shape  ( pipe , tube )
   a hollow cylindrical shape
     The dentist used a small tube to suction excess saliva during the procedure.
   The dentist used a small tube to suction excess saliva during the procedure.
   
4. [UK] An electric railway operating below the surface of the ground (usually in a city)  ( subway system [ N. American] , tube [UK] , underground [British] , metro , subway [ N. American] )
   an electric railway operating below the surface of the ground (usually in a city)
    In Paris the subway system is called the metro' and in London it is called the tube' or the underground'
   in Paris the subway system is called the metro' and in London it is called the tube' or the underground'
   
   
5. (anatomy) any hollow cylindrical body structure  ( tube , tube-shaped structure )
   (anatomy) any hollow cylindrical body structure
   

verb

1. Place or enclose in a tube  ( tube )
   place or enclose in a tube
   
2. Ride or float on an inflated tube  ( tube )
   ride or float on an inflated tube
    We tubed down the river on a hot summer day
   We tubed down the river on a hot summer day
   
3. Convey in a tube  ( tube )
   convey in a tube
    Inside Paris, they used to tube mail
   inside Paris, they used to tube mail
   
4. Provide with a tube or insert a tube into  ( tube )
   provide with a tube or insert a tube into
   

 tub tub /ˈtʌb/

noun

1. () A relatively large open container that you fill with water and use to wash the body  ( bathing tub , bathtub , tub )
   a relatively large open container that you fill with water and use to wash the body
    She filled the bathtub with warm water and bubbles
   She filled the bathtub with warm water and bubbles
   
   
2. () A large open vessel for holding or storing liquids  ( vat , tub )
   a large open vessel for holding or storing liquids
   
   
3. The amount that a tub will hold  ( tub , tubful )
   the amount that a tub will hold
    A tub of water
   a tub of water