نام روزهای هفته‌ی فرنگی از گاهنامه‌ی کهن ايرانی برگرفته شده است
نام روزهای هفته در ايران کهن بدين گونه بوده است:

کیوان شید = شنبه
مهرشید = یکشنبه
مه شید = دوشنبه
بهرام شید = سه‌شنبه
تیرشید = چهارشنبه
هرمزشید = پنج‌شنبه
ناهیدشید یا آدینه = جمعه

اينک با بررسی ريشه‌های اين واژگان به اين بر‌آيند ساده می‌رسيم:

کیوان شید = شنبه

Saturday = Satur + day
Saturn = کیوان
مهرشید = یکشنبه
Sunday = Sun + day
Sun = خور (خورشید) = مهر
مه شید = دوشنبه
Monday = Mon + day
Moon = ماه
بهرام شید = سه‌شنبه
Tuesday = Tues + day
Tues = god of war = Mars = بهرام
Tuesday
O.E. Tiwesdæg, from Tiwes, gen. of Tiw "Tiu," from P.Gmc. *Tiwaz "god of the sky," differentiated specifically as Tiu, ancient Germanic god of war, from PIE base *dyeu- "to shine" (see diurnal). Cf. O.N. tysdagr, Swed. tisdag, O.H.G.ziestag. The day name (second element dæg, see day) is a translation of L. dies Martis (cf. It. martedi, Fr. Mardi) "Day of Mars," from the Roman god of war, who was identified with Germanic Tiw (though etymologically Tiw is related to Zeus), itself a loan-translation of Gk. Areos hemera. In cognate Ger. Dienstag and Du. Dinsdag, the first element would appear to be Gmc. ding, þing "public assembly," but it is now thought to be from Thinxus, one of the names of the war-god in Latin inscriptions.
تیرشید = چهارشنبه
Wednesday = Wednes + day
 Wednes = day of Mercury  = Mercury = تیر
Wednesday
O.E. Wodnesdæg "Woden's day," a Gmc. loan-translation of L. dies Mercurii "day of Mercury" (cf. O.N. Oðinsdagr, Swed.Onsdag, O.Fris. Wonsdei, M.Du. Wudensdach). For Woden, see Odin. Contracted pronunciation is recorded from 15c. The Odin-based name is missing in German (mittwoch, from O.H.G. mittwocha, lit. "mid-week"), probably by influence of Gothic, which seems to have adopted a pure ecclesiastical (i.e. non-astrological) week from Greek missionaries. The Gothic model also seems to be the source of Pol. sroda, Rus. sreda "Wednesday," lit. "middle."
هرمزشید = پنج‌شنبه
Thursday = Thurs + day
 Thurs = Thor = day of Jupiter = Jupiter = هرمز
Thursday
O.E. Þurresdæg, perhaps a contraction (influenced by O.N. Þorsdagr) of Þunresdæg, lit. "Thor's day," from Þunre, gen. ofÞunor "Thor" (see Thor); from P.Gmc. *thonaras daga- (cf. O.Fris. thunresdei, M.Du. donresdach, Du. donderdag, O.H.G.Donares tag, Ger. Donnerstag "Thursday"), a loan-translation of L. Jovis dies "day of Jupiter," identified with the Gmc. Thor (cf. It. giovedi, O.Fr. juesdi, Fr. jeudi, Sp. jueves), itself a loan-translation of Gk. dios hemera "the day of Zeus."
ناهیدشید یا آدینه = جمعه
Friday = Fri + day
Fri = Frig = day of Venues = Venues = ناهید
Friday
O.E. frigedæg "Frigga's day," from Frige, gen. of Frig (see Frigg), Germanic goddess of married love, a West Germanic translation of L. dies Veneris "day of (the planet) Venus," which itself translated Gk. Aphrodites hemera. Cf. O.N. frijadagr, O.Fris. frigendei, M.Du. vridach, Du. vrijdag, Ger. Freitag "Friday," and the Latin-derived cognates O.Fr. vendresdi, Fr.vendredi, Sp. viernes. In the Germanic pantheon, Freya (q.v.) corresponds more closely in character to Venus than Frigg does, and some early Icelandic writers used Freyjudagr for "Friday." Black Friday as the name for the busy shopping day after U.S. Thanksgiving holiday is said to date from 1960s and perhaps was coined by those who had the job of controlling the crowds, not by the merchants; earlier it was used principally of days when financial markets crashed.