adverb
Indicates that something has already happened or is already the case by the time in question. Often used with past-tense or perfective expressions.
彼はすでに帰りました。
He has already gone home.
その本はすでに読んでしまった。
I've already finished reading that book.
adverb
Refers to something that was true or happened at an earlier time, often contrasted with the present. Common in formal or written contexts.
すでに述べたように、計画は変更されました。
As previously stated, the plan has been changed.
adverb
undeniably; in the first place
Used to emphasize that something is clearly the case or should be obvious, often with a nuance of 'to begin with' or 'needless to say'. Common in argumentative or explanatory speech.
すでに彼の実力は証明されている。
His ability has already been undeniably proven.
すでにその話は最初からおかしかった。
That story was strange in the first place.