From HomoExcelsior

1. an onion bulb; a tulip bulb. 2. A similar underground stem or root, such as a corm, rhizome, or tuber. 3. A plant that grows from a bulb. 4. the bulb of a syringe. 5. An incandescent lamp or its glass housing. 6. A rounded dilation or expansion of a canal, vessel, or organ.

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