expression, noun which may take the genitive case particle 'no'
Emphasizes that there is exactly one, often with a nuance of scarcity or uniqueness. Used as a prenominal modifier with の.
See also: たった
There is only one egg in the fridge.
He missed his only chance.
Combination of the adverb たった (only) and 一つ (one). The adverb たった is a contraction of ただ (only).