This is the adverb version of 未, so it means the same thing: not yet, or still, depending on the context.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn it with this kanji, so here a mnemonic to help you:
Someone's telling you "not yet... not yet.... not yet...". You have some food on your nose, but you're not allowed to eat it 今 (いま).
Note that this word can also be read まだ. However, いまだ is often written in kanji, while まだ is almost always written in kana. So when you see 未だ, it's a safe bet to read it as いまだ!
still can’t forget
something is still there
still don't understand
There’s still never been a person who’s lived to two hundred years old.
I’m still jet-lagged.
I’m not sure if I got the job yet.