What word is used to describe the possession of one dominant allele and one recessive allele?

Heterozygous is the word used to describe the possession of one dominant allele and one recessive allele. For example, in hybrid tall plant (Tt) genes are present. T is dominant gene and its allele t is recessive gene. In heterozygous organisms dominant allele is expressed and recessive allele is unexpressed in phenotype.

"do a testcross with a homozygous recessive plant."