since
for the reason that; because;

in the intervening period between
the time mentioned and the time under consideration

see another keyword links:

reason

when

period

time

mention

consideration

from, since

from, since, whence

already
since, as

Since you are here you'd better relax.
Since we have come, let us stay and enjoy it.
Since we are here, we may as well stay and make the best of it.

ever, since