Italian word blu comes from Proto-Indo-European *bʰleh₁-, Proto-Indo-European *bʰlēw, and later Proto-Germanic *blēwaz (A dark bluish or grey colour, black. Blue.)
| Dictionary entry | Language | Definition |
|---|---|---|
| *bʰleh₁- | Proto-Indo-European (ine) | |
| *bʰlēw | Proto-Indo-European (ine) | |
| *bʰlē-wo- | Proto-Indo-European (ine) | |
| *bʰlewas | Proto-Indo-European (ine) | light-coloured, blond, yellow |
| *blēwaz | Proto-Germanic (gem-pro) | A dark bluish or grey colour, black. Blue. |
| *blāo | Frankish (frk) | |
| blāo | Frankish (frk) | |
| *blāw | Frankish (frk) | Blue. |
| *blavus | Vulgar Latin (la-vul) | |
| *blavus | Latin (lat) | Blue. |
| bleu | Old French (842-ca. 1400) (fro) | |
| bleu | Middle French (ca. 1400-1600) (frm) | Blue Blue. |
| blu | Italian (it) | Blue The colour blue. |