already
Word family
Synonym discussion
Sense: adverb/1
'Already' shows that something was true or finished by a certain time: 'We had already eaten by six.' 'Previously' is more formal and appears more often in writing, reports, or careful explanation. 'Before' is broader and may simply show earlier time, usually with another clause or phrase, as in 'I met her before lunch.' 'By then' points to a later reference point inside a story, not directly to now. So 'I already know' sounds natural in daily speech, while 'I previously knew' sounds distant. You can say 'By then, the shop had closed,' but 'already' is better when the main idea is completed state by that time.
Etymology
'Already' began as the Middle English phrase 'all ready', meaning something like 'completely prepared' or 'by this time'. Over time, English joined the two words into one adverb. In modern English, the word is mainly used to talk about time or to show surprise that something happened earlier than expected.