ARAM - What does ARAM mean in LoL?

ARAM stands for "All random all mid." See an example of how people use it.
League of Legends (LoL) players use ARAM to refer to the All Random All Mid game mode. In this mode, players are assigned random champions (from their pool of owned champions) and forced to fight in a single lane.

Forget Loldle, there's a new League of Legends quiz in town

Updates to ARAM

dev: ARAM Changes Roundup – League of Legends

Ranking Every Champion in League of Legends ARAM

What is the point of Aram in lol?

dev: ARAM Changes Wrap-Up – League of Legends

LoL ARAM: A Player Guide

Why I only play League of Legends' ARAM game mode now

Aram is not playable at all - General Discussion - Heroes of the

Surrender at 20: Howling Abyss ( New ARAM Map + Match Making Queue

League of Legends Patch 13.4 ARAM Death Timers Explained

Howling Abyss (League of Legends), League of Legends Wiki