A concrete noun is something more real, less abstract, than an abstract noun.  It may not be a physical object like a table or a car, 
but its sense is adjectrive-based than, say, the abstract nouns 'beauty' or 
'a departure'.
See also: how to make
abstract nouns with -ság from adjectives, 
and making nouns with -ás from verbs.
 
The endings -at, -et
may be used to create concrete nouns that usually express the result of an action.
- 
mond
(to) say
 
- 
mondat
(a) sentence
 
- 
él
(to) live
 
- 
élet
(a) life
 
- 
ír
(to) write
 
- 
irat
(a) document
 
- 
felel
(to) answer
 
- 
felelet
(an) answer
 
- 
felad
(to) give up
 
- 
feladat
(a) task, exercise