0 completely sure of something, or knowing without doubt that something is true -- уверенный, убежденный
[ + (that) ] I feel absolutely certain that you're doing the right thing.
[ + question word ] Nobody was certain how the accident had happened.
1 to know something without doubt -- знать/говорить наверняка
We don't know for certain whether she's coming.
2 sure to happen, to do something, or to be true -- несомненный
3 used to refer to a particular person or thing without naming or describing them exactly -- определенный, некоторый
4 used before a noun to mean existing, but difficult to describe the exact quality or amount -- некий, некоторого рода
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
Мы можем выполнить ее шаг за шагом, какой бы длинной ни была дорога, и она не может быть завершена, какой бы короткой ни была дорога, если вы даже не обозначите свой след.