incense: the fragrant spice blend burned as an offering to God, and the burning of it
In the Bible incense is not room fragrance. It is a costly blend of spices with a fixed recipe, burned on a small gold altar inside the sanctuary every morning and evening, and Israel was forbidden to mix it for ordinary use. The Greek word covers both halves of that picture: the fragrant material itself, and the daily offering in which it went up in smoke. Which of the two is in view depends entirely on the sentence, and no English word makes the difference visible.
Luke uses it for the moment rather than the powder. While Zechariah is inside at the gold altar, the whole crowd stands praying outside "at the hour of the incense" (Luke 1:10), and the angel appears beside the altar named for it (Luke 1:11). The rite and the substance are bound so tightly together that one word does the work of both.
Revelation then says out loud what the praying crowd already assumed. The golden bowls the elders hold are full of incense, "which are the prayers of the saints" (Revelation 5:8), and in Revelation 8:3 and 8:4 an angel is given a great quantity of it to add to the prayers of all God's people, so that the smoke rises before God along with what they have asked. The image works because of what incense physically does: it is sweet, it is expensive, and it goes up.
One use has nothing to do with worship at all. In the cargo list of goods the merchants can no longer sell, incense sits among cinnamon, myrrh, and frankincense (λίβανος) as a luxury import (Revelation 18:13). That verse is a useful reminder that this was traded, expensive material before it was ever a symbol of anything.