Marbling
Etymology
From "marble," via Latin and Greek "marmaros" (shining stone). The white streaks of intramuscular fat running through red meat resemble the veining of polished marble, and the word borrowed the stone’s look to describe them.
noun · /MAR-bling/
The fine flecks and veins of fat distributed within a cut of meat.
What it names
The single feature that most predicts how juicy, tender, and flavorful a steak will be.
Example
The heavy marbling in the ribeye melts as it cooks, basting the meat from within.
Related idea
Contributes to mouthfeel: as marbling melts, it coats the tongue and gives beef its rich, lubricated texture, distinct from the plain taste of the meat itself.