For certain and In sight

For certain adverb - Definitely or positively (`sure' is sometimes used informally for `surely').

In sight and for certain are semantically related. In some cases you can use "In sight" instead an adjective phrase "For certain".

In sight adjective - At or within a reasonable distance for seeing.

For certain and in sight are semantically related. Sometimes you can use "For certain" instead an adjective phrase "In sight".