Real Dictionary

cushion
countable noun: A cushion is a fabric case filled with soft material, which you put on a seat to make it more comfortable.

cushion in American English
a pillow or soft pad for sitting or kneeling on, or reclining against; specif., a removable one forming part of a sofa, chair, etc.
to provide with a cushion or cushions
noun: a soft bag of cloth, leather, or rubber, filled with feathers, air, foam rubber, etc., on which to sit, kneel, or lie
transitive verb: to place on or support by a cushion

cushion in British English
to place on or as on a cushion
noun: a bag made of cloth, leather, plastic, etc, filled with feathers, air, or other yielding substance, used for sitting on, leaning against, etc

cushion in Hospitality
noun: A cushion is a fabric case filled with soft material, which you put on a seat to make it more comfortable.

cushion in Mechanical Engineering
verb: Something that cushions a part or object when it hits something protects it by reducing the force of the impact.