What is "nonselectively"

adv. 1 In a nonselective manner 2 (context chemistry English) Describing the isotopic labelling of a compound in which the position and numbering of the labelled nuclides are undefined; such a compound is ''nonselectively labelled'' alt. 1 In a nonselective manner 2 (context chemistry English) Describing the isotopic labelling of a compound in which the position and numbering of the labelled nuclides are undefined; such a compound is ''nonselectively labelled''