What does the root word haplo mean?

The root word "haplo" comes from the Greek word "ἁπλοῦς" (haplous), which means "single" or "one".

It is commonly used in biological terms to denote something that has a single set of chromosomes, like in "haploid" (a cell or organism with a single set of chromosomes) or "haplotype" (a set of alleles at linked loci on a chromosome).