A soothing aroma — the 'restful, pleasing smell' of an offering (nichoach shares the root nuach, 'to rest,' the root behind Noah's name). Its FIRST appearance is Noah's burnt-offering after the flood: 'Jehovah smelled the soothing aroma' and swore never again to curse the ground (8:21). Leviticus makes the same phrase the refrain of the whole sacrificial system (1:9, 13, 17) — what Noah did once at the altar becomes Israel's daily worship. KJV 'a sweet savour.' → first discussed at Lev 1:9