what is an 11 lettered word that means "a cell without a membrane?

The word you're looking for is "prokaryotic." Prokaryotic refers to a type of cell that lacks a membrane-bound nucleus.

To find this word, you can break down the problem into smaller steps:
1. Start by understanding the concept you're looking for— in this case, a cell without a membrane.
2. Think about the characteristics of such cells and try to recall any terms or words related to this concept. In this case, "prokaryotic" is a common term in biology that fits the description.
3. You can verify this answer by counting the number of letters in the word "prokaryotic." It has 11 letters, which matches your initial requirement.

Remember that actively thinking about the concept, recalling related terminologies, and counting the number of letters are helpful strategies when searching for specific words or answers.