1. A terminology-based system, implemented on a server, for supporting data entity definition, which defines a data entity of a concept by setting at least one qualifier that specifies the concept, the terminology-based system comprising: a terminology system management unit which stores a terminology system structured with a plurality of concepts and term relations which are relationships between the concepts; a data entity storage unit which stores data entities of the concepts defined by setting at least one qualifier; a data entity definition unit which, if a concept is selected from the terminology system, defines the data entity of the selected concept by setting qualifiers; and a qualifier recommendation unit which searches for data entities of the same concept or a related concept to the selected concept, and recommends qualifiers of the searched data entities by a priority, wherein the related concept is connected to the selected concept within the terminology system by the term relations; wherein a data entity definition unit sets some of the recommended qualifiers as qualifiers of the data entities of the selected concept; and wherein the priority of a qualifier q i , which belongs to the searched data entities, is obtained as a sum Q i (C M ) from formula 1: Q i ⁡ ( C M ) = ∑ R k M ∈ R ⁡ ( C M ) ⁢ ⁢ 1 W ⁡ ( R k M ) · q i ⁡ ( C k ) [ Formula ⁢ ⁢ 1 ] where C M is the selected concept, C k is the same concept as or the related concept to the concept C M , q i (C k ) is the sum of the rating weights of the data entities of the concept C k having a qualifier q i , W(R k M ) is the sum of the relation weights of the term relations from concept C M to the concept C k , R K M is the term relations from the concept C M to the concept C k , and R(C M ) is a set of term relations between the concept C M and the same concept as or the related concept to the concept C M .