not able to make heads nor tails (out) of (something)

not able to make heads nor tails (out) of (something)

Failing or unable to understand, decipher, or make sense (of something). We tried identifying the hieroglyphs on the ancient tablet, but they were so archaic that we weren't able to make heads nor tails of it. See if you can figure out what this contract is saying—I wasn't able to make heads nor tails out of all that legal mumbo jumbo.

See also: able, head, make, nor, not, of, tail