What is the past tense for word tremulous?

The word "tremulous" is already an adjective describing a state of being, so it doesn't have a past tense.

If you're looking for a verb, you might be thinking of "tremble", which means to shake involuntarily. The past tense of "tremble" is "trembled".

Here's an example:

* Present Tense: The bird trembles on the branch.

* Past Tense: The bird trembled on the branch when the cat approached.