Plaintive (adjective)

1. Expressing sorrow or sadness in a quiet, gentle way.
2. Having a sad or mournful sound.

Origin:

Late middle english: from old french, from plainte "complaint", from latin planctus, from plangere "to beat one"s breast, lament".

Examples:

1. The plaintive cries of the seagulls.
2. She spoke in a low, plaintive voice.
3. He sang a plaintive song of lost love.
4. The child's plaintive cries could be heard throughout the house.
5. The wind was howling in a plaintive manner.