| NHIF | National Head Injury Foundation |
|---|---|
| NMF | N-methylformamide; National Medical Fellowship; National Migraine Foundation; nonmigrating fraction |
| NRF | Neurosciences Research Foundation; normal renal function |
| NSF | National Science Foundation; nodular subepidermal fibrosis |
| OIF | observed intrinsic frequency; oil immersion field; Osteogenesis Imperfecta Foundation |