as needed

[adv] - according to need (physicians use PRN in writing prescriptions)
Found on http://www.webdictionary.co.uk/definition.php?query=as%20needed

as needed

as required adverb according to need (physicians use PRN in writing prescriptions); `add water as needed`
Found on http://wordnetweb.princeton.edu/perl/webwn?s=as%20needed
No exact match found