Days of the week in East Asia

Japanese and Korean name 5 days of the week using words for traditional elements (fire, water, wood, metal, earth) and use the words for moon and sun in naming Sunday and Monday. Both languages combine those components with a 2^nd component meaning day of the week.

Table 1 shows the Japanese and Korean names in both native and romanised scripts, highlighting the 1^st components in bold type.

Table 2 shows the meanings of the 1^st components (in romanised script only). As the tables show clearly, the Japanese and Korean components come from the same source (namely Chinese).

Table 1. Japanese and Korean days of the week

For more on The Korean writing system hangul, please see Hangul Day – Language Miscellany

Table 2. Component meanings: Japanese and Korean

Mandarin and Vietnamese

Mandarin and Vietnamese also name 6 of the 7 days with 2 components:

• a 1^st component meaning ‘week’ (Mandarin) or ‘order’ (Vietnamese); and
• a 2^nd component being a numeral.

Table 3 shows the Mandarin names and table 4 shows the Vietnamese names.

Table 3. Mandarin days of the week

Mandarin names for 6 of the 7 days of the week use the pattern 星期 (xīngqī—meaning ‘week’) + numeral. For example, Monday is 星期一 (xīngqī yī—’week one’).

The word for Sunday also uses 星期 (xīngqī) as the 1^st component but with 天(tiān—‘sky/heaven’) or (rì— ‘day/sun’) as the 2nd component.

Table 3. Mandarin days of the week

For all 7 days, it is also possible to use 周 (zhōu) or 禮拜 (lǐbài, or simplified form 礼拜) as the 1^st element instead of 星期 (xīngqī).

For more on Mandarin numbers, please see Numbers in Japanese and Chinese – Language Miscellany

Vietnamese

Vietnamese names for most days of the week use the pattern thứ (‘order’) + numeral. For example, Monday is thứ Hai (‘order two’). The same pattern is used in creating ordinal numbers (‘second’, ‘third’ etc).

The exception is the word for Sunday, regarded as the 1^st day: chủ nhật (‘master/owner day’). Similarly, the ordinal ‘first’ is thứ nhật.

Table 4. Vietnamese days of the week

The normal Vietnamese word for ‘four’ is bốn (word) but Wednesday is always thứ tư and the ordinal ‘fourth’ is also thứ tư, using the Sino-Vietnamese numeral form tư.

For more on Vietnamese numbers, please see Numbers in Vietnamese and Khmer – Language Miscellany

Connection with planetary names

The names of the 5 ‘elements’ used in the Japanese and Korean names of days (and used in former Chinese names) also appear in the names of planets (or of the Moon).

In some western European languages (particularly Italian and other Romance languages), the names of most days of the week are derived from the names of Roman gods, which are also names of planets.   

Strikingly, for most planets, their Romance name and their Chinese-derived Japanese and Korean names each link to the same day of the week. For example:

• Mars is the source of Italian martedì (Tuesday)
• the Japanese and Korean names for Mars include a word for fire. The same word also appears in the Japanese and Korean names for Tuesday.

Table 5 shows the days of the week, their Italian names and the planetary names derived from the same divine name as their Italian name. The final column shows the related element in the Japanese and Korean words for both the same day (as in table 2) and the same planet.  

Table 5. days of the week and planetary names

The name Saturn is reflected in English Saturday, but the corresponding Italian word means ‘sabbath’. The old Chinese word for ‘earth’ is reflected in the Japanese and Korean words for both Saturday and Saturn.