既然
jì rán
since; now that; given that
conjunction
Example
既然你已经决定了，我就不再劝你了。
Jì rán nǐ yǐjīng juédìng le, wǒ jiù bù zài quàn nǐ le.
Since you've already decided, I won't try to persuade you anymore.
A useful conjunction for expressing logical reasoning based on existing circumstances. Often followed by 就 (jiù) in the second clause to show the natural conclusion.