What's the noun form of "insufficient"?
This is a list of synonyms for layman or non-expert. All are nouns. Each is linked to a corresponding dictionary definition.
- amateur
- dilettante
- novice
- apprentice
- acolyte
Acolyte is probably the least suitable choice on the list.
EDIT
A sixth suggestion, per the comments, is
- know-nothing
As has been pointed out, the "noun form" of insufficient is insufficiency.
But from his supplementary comment it's clear OP actually seeks either a noun equivalent to someone who has insufficient knowledge of the currently discussed topic, or an adjective describing such a person.
For the noun form, there are two different sets of words. Those which imply that the person doesn't yet have the relevant knowledge (but probably will eventually), such as novice, apprentice, beginner, learner, etc. And those which imply he may never become knowledgeable on the subject, such as nonprofessional, amateur, dilletante, outsider, layman, etc..
For the adjective, I would go for inexperienced. Per my own comment, we often use inexperienced and inadequate without bothering to specify exactly the specific area of knowledge or capability which is lacking. Both those terms are often used of sexual experience/prowess, for example, in contexts where that meaning may not be explicitly stated. In OP's context, it would be clear that the missing "experience" is effectively "knowledge/familiarity with the current subject".
Are you looking for insufficiency?
Noun
The lack of sufficiency; the shortage or inadequacy of.