WordNet (r) 3.0 (2006):

welfare state
    n 1: a government that undertakes responsibility for the welfare
         of its citizens through programs in public health and
         public housing and pensions and unemployment compensation
         etc.

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "welfare state":
   ADC, Medicaid, Medicare, absolute monarchy, aristocracy, autarchy,
   autocracy, autonomy, child welfare, coalition government,
   colonialism, commonweal, commonwealth, constitutional government,
   constitutional monarchy, cradle-to-grave security, democracy,
   dictatorship, dominion rule, duarchy, duumvirate, dyarchy,
   federal government, federation, feudal system, garrison state,
   gerontocracy, guaranteed annual income, guaranteed income,
   health insurance, heteronomy, hierarchy, hierocracy, home rule,
   limited monarchy, martial law, meritocracy, militarism,
   military government, mob rule, mobocracy, monarchy, neocolonialism,
   ochlocracy, old-age assistance, oligarchy, pantisocracy,
   patriarchate, patriarchy, police state, public assistance,
   public welfare, pure democracy, regency, relief,
   representative democracy, representative government, republic,
   self-determination, self-government, sickness insurance,
   social democracy, social insurance, social security,
   social service, social welfare, social work, socialized medicine,
   state medicine, stratocracy, technocracy, thearchy, theocracy,
   totalitarian government, totalitarian regime, triarchy,
   triumvirate, tyranny, unemployment compensation,
   unemployment insurance, welfare, welfare capitalism,
   welfare payments, welfare statism, welfare work, welfarism,
   womb-to-tomb security