Full Idea
The 'Dao' (tr 'Way) has five meanings: 1) path or road, 2) mode of doing something, 3) account of how to do something, 4) the right way to live, and 5) the ultimate metaphysical entity responsible for nature, and how it should be.
Gist of Idea
The Dao (Way) first means the road, and comes to mean the right way to live
Source
Bryan van Norden (Intro to Classical Chinese Philosophy [2011], 1.III)
Book Reference
Norden,Bryan van: 'Intro to Classical Chinese Philosophy' [Hackett 2011], p.11
A Reaction
[compressed] So it is essentially metaphorical, just like the English 'way to do a thing'. Number 5 seems a rather large leap from the others, and most discussion seems to centre on number 4. The Chinese hoped for consensus on the Dao.