NIST  National.Institute.of.Standards.and.Technology
N-Layer  N.is.set.for.any.layer.name.(such.as.link,.network,. etc.).or.for.the.initial.(e..g..N-SDU.means.LSDU. at the link layer). OSI model definition.
NL Low-Pressure.Gas.Generator.RPM NLM Network-Loadable.Module NLP Network.Layer.Protocol NLR Netherlands.National.Aerospace.Laboratory NLT Not.Less.Than NM or NMI Nautical.Mile NM Network.Management NMC National.Meteorological.Center NMCCD Network.Management.Category.Class.Diagram NMCD Network.management.Category.Diagram NMF Network.Management.Function NMIRS Network Management Interface Requirements
Specification
NMOS  N-type Metal Oxide Semiconductor
NMP  Network.Management.Plan
NMS  Network.Management.System
NMT  Not.More.Than
NNN  “N”s.are.used.to.represent.a.generic.number..
Typically, multiple Ns represent a frequency.
NOAA  National Oceanic and Atmospheric Administration
NOC  Notice Of Change
NOCAR  North Atlantic Oceanic Concept and
Requirements
NOCC  National Operations Control Center
NO COM  No Communication. A NO COM annunciation indicates.that.a.downlink.message.has.not.been. acknowledged.in.an.ACARS.system.
NOI  Notice of Inquiry

Noise  Undesired.random.electromagnetic.disturbances. 
or.spurious.signals.that.are.not.part.of.the. 
transmitted.or.received.signal. 
NOP  Notification of Problem 
NOPAC  North Pacific 
NOTAM  Notice.to.Airmen 
NOTUS  Notice.to.Users.(ARINC) 
NPA  Non-Precision.Approach 
NPDU  Network.Protocol.Data.Unit 
NPRM  Notice.of.Proposed.Rule.Making 
NR  Network.Router 
NRD  Network.Routing.Domain 
NRP  National.Route.Program 
NRZ  Non-Return.to.Zero 
NS  Network.Service 
NSAP  Network.Service.Access.Point 
NSDU  Network.Service.Data.Unit 
NSEU  Neutron.Single.Event.Upset 
NSSL  National.Severe.Storms.Laboratory 
NTF  No.Trouble.Found..(Referring.to.testing.or. 
checkout.of.unit/module.) 
NTIA  National.Telecommunications.and.Information.