olemus
Wiktionary:
operation
1. the method by which a device performs its function.
It is dangerous to look at the beam of a laser while it is in operation

Merriam-Webster:
operation
1: performance of a practical work or of something involving the practical application of principles or processes
Practice until you can go through the whole operation without hesitation or thinking.
2c: a method or manner of functioning
a machine of very simple operation

näiteid
ISO 16923 jm:
normaalne töö
olukord, kus seadmestik töötab talle kavandatud parameetrite piires
= normal operation
situation when the equipment is operating within its design parameters