I just bought some led bulbs to replace the cfls. The instructions with one set of bulbs state "Do not use in enclosed fixtures." The fixture in the kitchen ceiling is not recessed but it has a dome that appears to fit into the ring containing the light socket. The fixture in the bedroom is clearly not enclosed since the cover hangs down a bit and I can see the bulbs currently installed. Is the dome fixture enclosed? Or does this term only apply to weather-proof outside fixtures?

No not just outside fixtures. An enclosed fixture could/would be a globe that traps heat. From your description of the litchen fixture I would not use that bulb.