Noble
Invaluable
い adjective
This is a single kanji with an い on the end, meaning you know it's probably an adjective. This adjective describes things that are valuable in a way that transcends monetary worth, so it means noble or invaluable.
While 尊い is used for things you honor from the heart, 貴い leans toward a dignified, noble kind of value — the kind tied to high status or social rank. Because of that, you may encounter 貴い in stories about historical class systems or old social hierarchies. It doesn't appear as commonly as 尊い in modern Japanese, but you may still see it in descriptions of someone's noble presence or the sense of dignity they give off.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. This has the same reading as 尊い (revered, noble), so if you remember that, you can read 貴い too! In case you forgot, here's a mnemonic to help you:
How can you tell if someone comes from a noble background? Just check their toe toe (とうと). Most noble families are pretty inbred, so a lot of their members will have a big toe (the long とう) with another small toe growing out of it (short と). This is a common birth defect among inbred aristocrats. Of course, from their point of view, it's invaluable proof of how noble and superior they are.
貴いお方
a noble person
貴い身分
noble status
貴い行い
noble deed
命ってのはベーコンと同じくらい貴いものなんだよ。
Life is as precious as bacon.
彼は生まれながらにして貴い身分を持っていた。
He was born into the nobility.
お顔が貴すぎて、近づくのもためらってしまう。
His face is so noble and divine that I hesitate to approach.
王はその若者の貴い行いに感動しました。
The king was moved by the young man's noble act.