乱麻 literally means 'tangled hemp' but is almost always used figuratively as a noun to describe a chaotic, messy situation—like a jumbled knot that's hard to untangle. It commonly appears in the fixed phrase 一团乱麻 (yī tuán luàn má, 'a tangled mess') and in the idiom 快刀斩乱麻 (kuài dāo zhǎn luàn má, 'cut the tangled hemp with a sharp knife', meaning to decisively solve a complicated problem). You cannot use 乱麻 as a general adjective for 'messy' (use 乱 or 乱七八糟 instead); it stays a noun that names the mess itself.