existing

The word “existing” means currently in existence; present now. In plain terms, already there, right now, as opposed to something new or planned.

“Existing” is pronounced ihg-ZIHS-tihng (/ɪɡˈzɪstɪŋ/ in IPA).

Here is “existing” used in a sentence: “The new policy will replace all existing regulations.”

“Existing” is an adjective.

“Existing” is a very common word in modern English, usually learned at around the B2 level.

Both mean present in reality, but existing is far more common and natural in everyday use, as in 'existing customers'. Existent is rarer and more formal or philosophical. In most writing, existing is the better choice; existent tends to appear only in academic or technical contexts.

Existing means something is present in reality right now: it exists. Current emphasises that something belongs to the present moment as opposed to the past or future. They often overlap, so 'existing rules' and 'current rules' can mean the same. But current stresses timing, while existing stresses presence.

You might say 'we will upgrade the existing system rather than build a new one', or 'existing members get a discount'. It typically describes something already in place before a change or addition. Common pairings include existing customers, existing conditions, existing law, and existing buildings.

The opposite depends on context. When existing means 'already in place', its opposite is new, proposed, or planned, as in a new system versus an existing one. When it means 'present in reality', the opposite is nonexistent, imaginary, or hypothetical. So the antonym shifts with the sense you intend.