An ancestral line is a family line that traces back to one's ancestors. It is often referred to as a PEDIGREE, which is an 8-letter word. A STEM is the 4-letter word used to describe the main part of the ancestral line, from which all other branches originate. The STRAIN is the 6-letter word used to describe the individual branches of the ancestral line. Together, these three words describe the concept of an ancestral line, which is a family line that traces back to one's ancestors.