Yes, BULB is a Scrabble word!

noun

1. a modified bud consisting of a thickened globular underground stem serving as a reproductive structure
2. electric lamp consisting of a transparent or translucent glass housing containing a wire filament (usually tungsten) that emits light when heated by electricity
3. a rounded part of a cylindrical instrument (usually at one end)
4. anything with a round shape resembling a teardrop
5. lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata)
6. a rounded dilation or expansion in a canal or vessel or organ