Would it be really unsafe to use an 18watt bulb on a lamp which recommends 10 watt?

I am wondering if the 18W CFL is too big. If it is not too big, then it is alright to use. CFL's get bigger as the wattage goes up. Otherwise, it's 100% alright to use.

What?

-I just bought a lamp that recommends 40 watt max type b (teardrop shape) light bulb & 10watt max CFL-

How can your light fixture support two types of wattage? Unless you mean its the light fixture with the two lamps.

Answer - Yes you can safely put an 18W bulb in a 40W socket but not in a 10W socket.