This is the 14803rd most frequent Russian word.
плотном
The word "плотном" is the prepositional case of "плотный," which means "dense," "thick," or "solid" in English.
Here, 'плотном' is an adjective describing the noun 'графике', indicating its density or compactness.
В плотном графике нет времени на отдых.
In the tight schedule, there is no time to rest.
In this sentence, 'плотном' qualifies 'лесу', expressing the physical density of the forest.
Мы остановились в плотном лесу.
We stopped in a dense forest.
Here, 'плотным' is used as a predicate adjective describing 'Описание', suggesting intricacy or richness in details.