Is solvent if the person is able to pay all the person's debts, as and when they become due and payable.
Who is not solvent is insolvent.
The two main approaches to determine whether a company or an individual is insolvent are:
A "cash flow" test, which looks to whether there is sufficient cash (and other realisable assets) available to a company (or a person) to pay creditors as debts fall due for payment.
A "balance sheet" test, which looks to the overall asset position of a company (or a person) and assesses solvency by reference to the value of assets in comparison to total liabilities.