1. A word, phrase, or manner of speaking that is no longer in common use due to age or being out of date
The word 'thee' is an obsolete expression in modern English.
A palavra 'vós' é uma expressão obsoleta no português moderno.
2. Archaic or antiquated language that has fallen out of favor in contemporary usage
Using 'forsooth' would be considered an obsolete expression by today's standards.
Usar 'porventura' seria considerado uma expressão obsoleta pelos padrões atuais.