This is the 9887th most frequent Russian word.
ад
Hell.
The word 'ад' here is used metaphorically to describe a place of extreme discomfort or suffering.
Это место выглядело как настоящий ад.
This place looked like real hell.
The phrase 'круги ада' metaphorically refers to enduring extremely difficult situations, originating from the concept of circles of hell in Dante's literature.
Он говорил, что пережил все круги ада.
He said he went through all circles of hell.
In this context, 'ад' is used in its literal meaning, referring to the concept of an underworld as portrayed in various myths and religions.