Word to Word !

[rolesfamily]

λ > Tepee

[Master]

(Lambda to Tepee, that's a new one.)

Tepee > Hut

[PluMGMK]

Hut Rustic

[Master]

Rustic > Reactive

[PluMGMK]

Reactive Caesium

[Master]

(Had to go into Chemistry, my weakest Science)
Caesium > Iron
(Ok, I'm cheating a little, I'm only going there because I'm pretty sure that Iron is the most stable element)

[PluMGMK]

Iron is the most stable from the nuclear perspective, but in terms of Chemistry, it would probably be Helium.

Iron Celts

[Master]

(Well, that figures, seeing as I've just been studying Nuclear energy)

Celts > Romans

[PluMGMK]

Romans Latins

[Master]

Latins > Greek

[rolesfamily]

Greek > Yogurt

[Imco]

Greek + Yogurt > Ben and Jerry's Greek Frozen Yogurt?

[Harpic fraîcheur]

Yogurt Actimel

[rolesfamily]

Actimel > Yakult

[Reese Riverson]

Yakult > Yakut

[Master]

Yakut > Yoghurt

[Reese Riverson]

Yoghurt > Flavor

[Master]

Flavor > Flavour

[Reese Riverson]

Flavour > Colour

[Master]

Colour > Spectrum