yodan verb with 'su' ending (archaic), intransitive verb
to lie down (honorific, archaic)
Archaic honorific verb (sonkeigo) meaning 'to lie down'. Used in classical Japanese; in modern language, お休みになる or 横になる are used instead. Cross-referenced with 臥ゆ, an older form.
See also: 臥ゆ
In classical texts, a noble person's lying down may be respectfully expressed as 臥やす.
Alternate archaic spelling with やす ending, reflecting the classical yodan verb form.
Classical Japanese verb; the exact derivation is uncertain. The kanji 臥 means 'to lie down' and is conventionally associated with this meaning.