expression
Polite form of 他ならない. Emphasizes that something is exactly that and nothing else, often used in formal speech or writing.
See also: 他ならない
この成功は、皆様のご支援のたまものに他なりません。
This success is nothing other than the result of everyone's support.
彼こそが、この分野の第一人者に他なりません。
He is none other than the leading authority in this field.