Languor (noun)

1. A state of physical or mental weariness; lack of energy or enthusiasm.
2. A state of listlessness or indolence.

Origin:

Middle english, from anglo-french, from latin languor, from languere to be weak.

Examples:

1. The heat of the day caused a languor that made it difficult to focus on work.
2. The patient's illness left her in a state of languor and weakness.
3. The tropical climate induced a feeling of languor in the travelers.
4. The dancers moved with a languorous grace.
5. The slow music and dim lighting created a sense of languor in the room.