Milestone

Etymology

Literally a stone set beside a road every mile to tell travelers how far they had come, a practice dating to Roman roads. The figurative leap — any marker of progress along a longer path — was natural once roads were the model for any journey. The physical stone is nearly gone; the metaphor is everywhere.

noun · /MYL-stohn/
A significant checkpoint in a project or journey that marks meaningful progress.
What it names
It breaks a long, shapeless effort into visible stages, so a team can feel and prove momentum before the finish.
Example
Shipping the beta was our first real milestone after eight months of quiet building.
Related idea
A milestone marks progress but produces nothing on its own; a deliverable is the actual artifact. A milestone can also differ from a KPI, which measures ongoing performance rather than a one-time point reached.