What is "for all practical purposes"

adv. effectively, virtually

adv. in every practical sense; "to all intents and purposes the case is closed"; "the rest are for all practical purposes useless" [syn: to all intents and purposes, for all intents and purposes]

For All Practical Purposes (FAPP) is a pragmatic approach towards the problem of incompleteness of every scientific theory and the usage of asymptotical approximations.

Usually, when a physicist makes an approximation - which can't be justified on rigorous grounds - he or she tends to justify it by saying that the results obtained are good for all practical purposes (FAPP), meaning that they agree with our experience and approximation errors cannot be detected in practical measurements (for instance, if the error is smaller than the measurement resolution).

FAPP theories are incomplete or lackly-based theories that nevertheless have very high agreement with experiments and tend to be very useful for all practical purposes.