This is the 6319th most frequent Japanese word.
ゴロリ
"ゴロリ" means "lazing around" or "relaxing idly."
Here, ゴロリ expresses the sound or manner of lying down heavily or comfortably.
床にゴロリと寝転んでいた。
He was lying flatly on the floor.
ゴロリ conveys a sense of relaxation or laziness in this context.
午後は公園でゴロリとした時間を過ごした。
I spent a lazy time in the park in the afternoon.
In this sentence, ゴロリ describes the manner of falling down, emphasizing the heaviness or abruptness.