(1) For the purposes of this Act the expression “hypothec” means a security by way of hypothec or mortgage for the payment of any definite and certain sum of money advanced or lent at the time, or previously due and owing, or forborne to be paid, being payable, or for the repayment of money to be thereafter lent, advanced or paid, or which may become due upon an account current, together with any sum already advanced or due, or without, as the case may be.