What does "squab" mean?

Additional senses

1. 2.(Zoöl.) A neatling of a pigeon or other similar bird, esp. when very fat and not fully fledged.
2. 3.A person of a short, fat figure. Gorgonious sits abdominous and wan, Like a fat squab upon a Chinese fan. Cowper.
3. 4.A thickly stuffed cushion; especially, one used for the seat of a sofa, couch, or chair; also, a sofa. Punching the squab of chairs and sofas. Dickens. On her large squab you find her spread. Pope.
4. 5.With a heavy fall; plump. [Vulgar] The eagle took the tortoise up into the air, and dropped him down, squab, upon a rock. L'Estrange.
5. 6.To fall plump; to strike at one dash, or with a heavy stroke. [Obs.]