Scientifically, Genotype and Phenotype should be considered together as the genotype-phenotype map will be set according to the characteristics of each other.
The genotype is the specific genetic combination of what is under consideration, be it a cell, organism or individual, thereby containing all hereditary information. The phenotype can be seen in the physical characteristics themselves and is determined by genetics and also environmental factors so its definition would be all observed physical features and distinct biochemical characteristics such as blood-type.
Genetic inheritance cannot simply be ascertained by discernible and observed physical characteristics as identified in the phenotype due to the fact that there may be other non-observable traits present in the genotype which have not manifest themselves. Recessive and dominant phenotypes depend on alleles and so "masking" may take place so some characteristics may not be apparent. Hence a definition for genetic inheritance would be the acquired characteristics to which a cell or organism is predisposed through a parent or ancestor.
As genotype and phenotype are considered together and as (genetic) inheritance stems directly from there so is closely related to this discussion, I have given the definition. As eNotes does not allow multiple questions, please note to post your questions about the other definitions separately. Group them together (like this question) so that related definitions can be considered and given together.