фон

fairly common #4628B2

nounmasculineinanimateuncountable

1.
background, backdrop
Она́ сфотографи́ровалась на фо́не моря.
She had her photo taken against the sea.
Often with на фоне + genitive = 'against the background of'.
2.
background level, ambient level
Радиацио́нный фон в го́роде в но́рме.
The background radiation level in the city is normal.
In compounds: шумовой фон, радиационный фон, миграционный фон.
3.
(rare) phonphysics
Гро́мкость измеря́ется в фона́х.
Loudness is measured in phons.
Physical unit of perceived loudness.
4.
von (in German names)
Он изуча́л архитекту́ру фон Неймана.
He studied the von Neumann architecture.
Indeclinable; part of a German surname.

Examples

Это цвет, дополняющий основной фон.
This is a color that complements the main background.
На его фо́не я просто новичо́к.
Besides him, I'm simply a beginner.
Проблема рельефно выделялась на фоне остальных
The problem stood out clearly against the others.
Фон, подмалёвываемый художником, стал светлее к вечеру.
The background, being touched up by the artist, became lighter by evening.
На фо́не снега бе́лый кро́лик был неви́дим.
Against the snow, the white rabbit was invisible.
Фон, дорисовываемый художником, выглядел очень реалистично.
The background being filled in by the artist looked very realistic.
Художник, забеливший фон картины, начал новую работу.
The artist who had whitened the background of the painting began a new work.
Художник, затушевавший фон, добился глубины рисунка.
The artist, who had shaded the background, gave the drawing a sense of depth.

⚠️ Stress change.