1. (

• deceleration ,
• slowing ,
• retardation

) a decrease in rate of change; "the deceleration of the arms race" ;

2. (

• retardation

) the extent to which something is delayed or held back ;

3. (

• retardant ,
• retardent ,
• retardation

) any agent that retards or delays or hinders; "flame-retardant" ;

4. (

• retardation ,
• mental_retardation ,
• backwardness ,
• slowness ,
• subnormality

) lack of normal development of intellectual capacities ;

5. (

• slowdown ,
• lag ,
• retardation

) the act of slowing down or falling behind ;