tempered distribution
A mathematical term from functional analysis; a distribution that does not grow too fast at infinity, allowing the Fourier transform to be defined.
The Fourier transform of a tempered distribution is again a tempered distribution.
超関数 (distribution) is a more general concept; 緩増加超関数 is a specific subclass with growth restrictions.
Compound of 緩増加 (tempered growth) and 超関数 (distribution). The term is a direct translation of the English 'tempered distribution'.