creep up

US /kriːp ʌp/
UK /kriːp ʌp/
"creep up" picture
1.

忍び寄る, 徐々に上がる

to move slowly and quietly so as not to be noticed

:
The cat crept up on the bird.
猫は鳥に忍び寄った
Prices have been creeping up steadily.
物価は着実に上昇している