Ask HN: Jargon for "pure hourly rate"

I do a lot of development consulting on a contract basis. I have a basic rate that assumes that the initial contract negotiation process is out of pocket and that the client is free to take or leave my services at any time. I much prefer to offer a retainer: a minimum number of hours per month for some agreed period, and will reduce my rate to reflect that preference.

I feel like there's got to be a snazzy way to sum that up to some of my potential clients, and is at least a handle for future discussion with the rest.

So far, the best I've been able to come up with is "a la carte" rate, but that doesn't seem to hit the mark, exactly.

Do you know a common term for this "highest risk" hourly rate?