Grainy means having a rough texture of small particles. A grainy sauce, a grainy photograph, grainy footage.
In cooking it is a fault of sauces and custards, caused by the protein setting into clumps rather than staying smooth. In photography, grain is the visible particle structure of film, and digital images imitate it deliberately — grainy footage now reads as authentic, which is why it is added on purpose.
1adjectivegrainyHaving a rough texture of small particles.
“The homemade ice cream was a bit grainy because the sugar hadn't fully dissolved.”
2adjectiveshowingShowing visible particle structure, of an image.
“The only photo of the thief was a grainy picture from a security camera.”
grainy is a quality of texture.
Middle English greyny is grain plus -y. Grain comes from Latin granum, a seed.
Middle English
greyny
English, today
grainy
From Middle English greyny, equivalent to grain + -y. corny.
Etymology from Wiktionary, CC BY-SA