1. (

• certain

) definite but not specified or identified; "set aside a certain sum each week"; "to a certain degree"; "certain breeds do not make good pets"; "certain members have not paid their dues"; "a certain popular teacher"; "a certain Mrs. Jones" ;

2. (

• certain ,
• sure

) having or feeling no doubt or uncertainty; confident and assured; "felt certain of success"; "was sure (or certain) she had seen it"; "was very sure in his beliefs"; "sure of her friends" ;

3. (

• certain ,

) established beyond doubt or question; definitely known; "what is certain is that every effect must have a cause"; "it is certain that they were on the bus"; "his fate is certain"; "the date for the invasion is certain" ;

4. (

• certain ,
• sure ,

) certain to occur; destined or inevitable; "he was certain to fail"; "his fate is certain"; "In this life nothing is certain but death and taxes"- Benjamin Franklin; "he faced certain death"; "sudden but sure regret"; "he is sure to win" ;

5. (

• sealed ,
• certain ,

) established irrevocably; "his fate is sealed" ;

6. (

• certain ,
• sure

) reliable in operation or effect; "a quick and certain remedy"; "a sure way to distinguish the two"; "wood dust is a sure sign of termites" ;

7. (

• certain ,
• sure

) exercising or taking care great enough to bring assurance; "be certain to disconnect the iron when you are through"; "be sure to lock the doors" ;