A minterm is an AND expression involving all input variables in either inverted or non-inverted form.For one particular row the associated mintermis the only minterm which equals logic 1 on that row and only on that row.So for the row in the truth table were A is 1, B is 0 and C is 1 the minterm is A.B.C
Example minterms.
Each minterm uniquely defines one row of the truth table.