Scarlet is a brilliant red with a slight orange lean. Scarlet uniforms, a scarlet coat, turn scarlet.
It is the red of British army dress uniform, of a cardinal's robes and of poppies. Of a face it means deep red with embarrassment or anger: she went scarlet. The Scarlet Letter and scarlet woman are the literary and moral uses, both about sexual reputation and both dated. Note scarlet fever, the childhood illness named for the rash; and that scarlet was a kind of cloth long before it was a colour.
1adjectivescarletA brilliant, slightly orange shade of red.
“The guards wore scarlet jackets and tall black hats.”
2adjectivedeepDeep red in the face from embarrassment.
“She went scarlet and left the room.”
scarlet is a colour.
Medieval Latin scarlatum named an expensive woollen cloth, borrowed from Persian and Arabic. The cloth was often dyed red, and the colour took the fabric's name — so scarlet describes what something was made of before it described how it looked.
Proto-Indo-European
*sek-
Arabic
سِقِلَّات
fa-cls
سقرلات — a warm woollen cloth
Medieval Latin
scarlātum — scarlet cloth
Old French
escarlate — a type of cloth
Middle English
scarlet
English, today
scarlet
From Middle English scarlet, scarlat, borrowed from Old French escarlate (“a type of cloth”), from Medieval Latin scarlātum (“scarlet cloth”), of uncertain origin. This was long thought to derive from fa-cls سقرلات (“a warm woollen cloth”), but the Persian word (first attested in the 1290s) is now thought to be from Arabic سِقِلَّات, denoting very expensive, luxury silks dyed scarlet-red using the exceptionally expensive dye, first attested around the ninth century. The most obvious route for the Arabic word siqillāt to have entered the Romance languages would be via the Arabic-speaking Iberian region of al-Andalus, particularly Almería, where kermes was produced extensively; compare especially the dialectal form سِقِرْلَاط. The word then came to be used of woollen cloth dyed with the same dye. The Arabic word may itself be derived from Medieval Greek σιγιλλᾶτον, from Latin sigillātus (“a type of fabric”) literally “sealed; sealing”.
Etymology from Wiktionary, CC BY-SA
Practised in Colours & Patterns