Who Are Your Direct Descendants?

This questions has made me think carefully, for I often refer to being directly descended from a particular ancestor.

Historically I believe that originally the term was meant to refer to your father's father's ...., however over time, and the emancipation of women, then it now refers to all parents and grandparents, great grandparents .....and so on.

While I cannot refer to any document that defines this exactly, the consensus appears to be this:

The Four Descents:

1."collateral" - indirect, meaning pretty much any provable blood relative from the past. 

2."direct" or "lineal"  - any male or female who was your great-great-great-etc. grandparent,

3."in the direct male line" or "patrilineal"  - meaning the Y chromosome descent only, your father's father's father's father's father etc.

4."matrilineal"  - meaning your mother' mother's mother's mother etc. only.