もう一つ
Meanings
1
Used as a noun phrase meaning an additional item or instance. Often followed by a noun or used alone.
One more, please.
There is another problem.
2
Adverbial use meaning 'to an even greater degree'. Often used with adjectives or verbs to indicate a higher level than before.
Today is even colder than yesterday.
His explanation made the problem even more complicated.
3
Used in negative contexts to express that something is not quite satisfactory or falls short of expectations. Often appears as もう一つ~ない or もう一つだ.
See also: 今ひとつ
This dish is not quite flavorful enough.
His proposal is lacking something.