Languid– (adjective)
Definition: showing or having very little strength, energy, or activity
Source: http://www.merriam-webster.com/dictionary/languid
Found in: Quicksand
Passage: Long, soft white clouds, clouds like shreds of incredibly fine cotton, streaked the blue of the early evening sky. Over the flying landscape hung a very faint mist, disturbed now and then by a languid breeze. But no coolness invaded the heat of the train rushing north. The open windows of the stuffy day coach, where Helga Crane sat with others of her race, seemed only to intensify her discomfort.
After reading the definition I now understand that the word was used to describe a relaxed, slow and lazy breeze that passed by.