From The Collaborative International Dictionary of English v.0.48 :
Nonpayment \Non*pay"ment\, n.
Neglect or failure to pay.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
nonpayment
n 1: act of failing to meet a financial obligation [syn:
default, nonpayment, nonremittal]
2: loss resulting from failure of a debt to be paid [syn:
nonpayment, default, nonremittal] [ant: payment]
3: the deliberate act of failing to pay money; "his evasion of
all his creditors"; "he was indicted for nonpayment" [syn:
evasion, nonpayment] [ant: defrayal, defrayment,
payment]