In general, we know many more words than we use on a daily basis. A prime minister using a vulgar colloquial expression at the National Assembly for example. New words and expressions may or may not find a place into the dictionary. The older generation tends to adopt the vocabulary of the younger generation, which is an unusual phenomenon. The uncertainties about the meaning of each word make the new vocabulary fragile.
Opposite meanings work only for some words.
Exceptions stand out. This is why there are only a few examples such as the introduction of double negation, the formation of adverbs with the addition of the suffix -ment to adjectives, and the creation of the future tense. Shifts in pronunciation 3.1. A final consonant has been introduced in words like parking, lifting, jogging. This fact could be linked to the tendency to stress the first syllable of words.