1. A word, spelling, or grammatical structure that is no longer in common use, typically associated with older periods of a language
The word 'thou' is an obsolete form of 'you' in modern English.
A palavra 'thou' é uma forma obsoleta de 'you' no inglês moderno.
2. A linguistic variant that has been replaced by more contemporary usage
The spelling 'connexion' is now an obsolete form; 'connection' is standard.
A ortografia 'connexion' é agora uma forma obsoleta; 'connection' é o padrão.