The word 'reinforce' is a verb (reinforce, reinforces, reinforcing, reinforced). The noun form for the verb is 'reinforcement', which is a concrete or an abstract noun depending on use. Examples:
Concrete: The reinforcement that supports the steps has broken.
Abstract: He needs positive reinforcement when he behaves properly.
The plural of reinforce is reinforces.
weaken
The word omen is an abstract noun.
abstract
The word 'ugliness' is an abstract noun; a word for an opinion, a word for a concept.
you should reinforce that fence
The plural of reinforce is reinforces.
she was not listening so i had to reinforce the rules
must i reinforce to you the importance of telling the truth
"Erudite" is an abstract word for wise.
The abstract word for resentful is bitterness.
weaken
Yes, the word 'fun' is an abstract noun, a word for a concept.
The word 'independence' is an abstract noun, a word for a concept.
The word omen is an abstract noun.
abstract
Abstract