constant  
 adjective uk/ˈkɒn.stənt/ us/ˈkɑːn.stənt/
  (FREQUENT)      
 B2 经常发生的;连续发生的;连续不断的
happening a lot or all the time
  He's in constant trouble with the police. 他与警方麻烦不断。 
 machines that are in constant use 经常使用的机器 
 - More examples
 - I can't concentrate with Ann's constant chatter.
 - I have to combat this constant desire to eat chocolate.
 - I seem to have a constant compulsion to eat.
 - The constant noise drove me crazy .
 - The journalists were frustrated by her constant deflection of their questions.
 
  (STAYING SAME)      
 C2 恒久不变的;稳定的
staying the same, or not getting less or more
  We ran at a fairly constant speed. 我们保持了比较平稳的跑动速度。 
 The fridge keeps food at a constant temperature. 冰箱在恒温下保存食物。 
   (LOYAL)     
 (伴侣或朋友)忠实的,忠贞不渝的,始终如一的
A constant companion or friend who is loyal to you.
 constant      
noun [ C ]  mathematics, science specialized uk/ˈkɒn.stənt/ us/ˈkɑːn.stənt/
 常数;常量,恒量
a particular number or amount that never changes