These words refer to the working out or making clear of a puzzle or mystery. Solve means to answer a question or work out a problem, often one deliberately set, as an exercise: solving the ten mathematical equations set for homework. The word can refer also to explaining any set of events by finding a workable way of dealing with them or by seeing the deeper meaning behind them: solving the problem of peace through world diplomacy; solving the dilemma of accounting for the national debt by viewing it in terms of the national balance of payments. Unravel functions most nearly like this general sense of solve . The emphasis is on the untangling of a knotty problem, especially by means of research or analysis: an investigating body at work to unravel the motives of the assassin; an essay attempting to unravel the meaning of the difficult poem.

Decipher and decode are alike in specifically referring to the act of making intelligible a message that has been systematically garbled to confuse an unwanted reader: deciphering the radioed messages of the enemy; decoding the message by feeding it through the computer programmed to turn it into English again. In this context, decipher refers to translating messages scrambled according to a key or pre-arranged scheme, whereas decode refers to translating agree-upon symbols that may be arbitrary or random. Thus decoding normally requires a code book in which the plain text and encoded equivalents are listed; deciphering involves only knowledge of the key or system, e.g., 1 for A, 2 for B, etc. Decipher is more often used than decode in a metaphorical way, in which case it refers to explaining puzzling or enigmatic signs: finally deciphering the odd expression he had given her a minute before.