Abstract: The phenomenon of same term with different definitions exists widely in genetic teaching courses. The present paper was aiming at analyzing and discussing these problems. For example, the terms such as Y-linked inheritance, sex-limited inheritance, sex-influenced inheritance, haploid, polyploid and cumulative effect expression are very confused and chaotic in meaning, even mutually contradictory. This involves the accuracy of nomenclature. We presumed that the term of Y-linked inheritance cannot confuse with that of sex-limited inheritance, and that though the sex-limited factor and the sex-influenced inheritance gene are both located on autosome with some distance, but they are still different. Haploid refers to the gametophyte chromosome number an individual has, but does not equate to monoploid. Also we thought that polyploid represented the basic number of chromosome, such as triploid indicated for 3X. And, the cumulative effect refers to mutual accumulation function between the exponential quantitative characters of relevant genes.