hard to fathom

Translations
трудно понять
The complexity of the problem was hard to fathom.
Сложность проблемы было трудно понять.
Definitions
Difficult to understand or comprehend; something that is beyond one's ability to grasp or make sense of.
Words
hard

adjective
трудный
to

functional word
частица инфинитива
fathom

verb
понять