The article is devoted to the description of the quasi-abbreviation equivalence nest. The work substantiates the need to introduce the concept of a "quasi-abbreviation equivalence nest", clarifies the concept of an "equivalence nest" and expands the concept of a "pseudo-equivalence nest". A quasi-abbreviation equivalence nest is considered as a set of units formed as a result of pseudo-universalization and derivationally related to an abbreviation equivalent abbreviation and an abbreviated morphemic quasi-abbreviation. The study provides the basic concepts of the synchronous analysis of the abbreviation theory of the Experimental Laboratory for Research of Abbreviation Trends, on the basis of which the work is formed.