From Wikipedia on Insolvency:
"Insolvency is the inability of a debtor to pay their debt. Cash flow insolvency involves a lack of liquidity to pay debts as they fall due. Balance sheet insolvency involves having negative net assets—where liabilities exceed assets. Insolvency is not a synonym for bankruptcy, which is a determination of insolvency made by a court of law with resulting legal orders intended to resolve the insolvency.
A business may be cash-flow insolvent but balance-sheet solvent if it holds market liquidity assets, particularly against short term debt that it cannot immediately realize if called upon to do so. Conversely, a business can have negative net assets showing on its balance sheet but still be cash-flow solvent if ongoing revenue is able to meet debt obligations, and thus avoid default: for instance, if it holds long term debt. Some large companies operate permanently in this state."