expression, noun
just one person; only one
Emphasizes that there is only a single person, often with a nuance of loneliness or insufficiency. Used as a noun phrase or adverbial expression.
See also: たった
会場にはたった一人しかいなかった。
There was only one person in the venue.
彼はたった一人でその仕事をやり遂げた。
He accomplished the task all by himself.
たった is an adverb meaning 'only' or 'just', used with quantities. たった一人 combines it with 'one person' to form a set phrase.
Phrase composed of たった (emphatic 'only') + 一人 (ひとり, 'one person').