To make understandable
To find a solution for
To find the key to (a code, for example)
She couldn't decipher what he had to be feeling.
In the meantime, he'd learn to use the compass better and decipher the symbols.
She was able to decipher some of it after all the tests she'd been through.
Kiera looked at her, attempting to decipher her warning.
He never had to wonder how many men were rotating through her bed or when she was planning to stab him in the back or decipher the riddles she gave him as answers to important questions.