Insolvent describes that same money trouble, as a describing word — an insolvent company, an insolvent person — and it can also name them: an insolvent is someone (or a firm) that cannot pay what they owe. Solvent, without the in-, is the opposite: you can pay. Though actually, solvent has another, much more everyday meaning: a liquid that makes other things dissolve, like paint thinner. Students often land on the chemistry one first. In the money sense, insolvent is serious and formal. Newspapers and lawyers use it. Friends might say broke, but broke is looser and smaller: an empty wallet this week. Insolvent is about debts you cannot meet. It is not about puzzles (that is insolvable) and not about sleep.