firmly rooted

Translations
твердо укоренившийся
The tradition is firmly rooted in their culture.
Традиция твердо укоренившаяся в их культуре.
Definitions
Deeply established or entrenched, often referring to beliefs, values, or physical objects that are securely fixed in place.
Words
firmly

adverb
прочно
rooted

adjective
укоренившийся