I think figment only appears in “figment of your imagination” because figment means “something made up or contrived”, so the “of your imagination” is actually a bit redundant.
Are there any non-innocent bystanders?
The only time I have heard the word iota used is in the phrase “not one iota of difference.”
Popular use of the word postpartum seems to be limited to postpartum depression.
Because I am making a distinction between technical and popular use of terms. For the vast majority, these terms have uses restricted to certain associated words.