Over lunch yesterday, a few Singaporean friends and I were celebrating the fact that 'friend' is now a commonly used verb. Prior to the advent of Facebook, 'friend' as verb - pronounced closer to 'fren' - had been relegated to the realm of Singlish kid speak. For example:
Kid 1: I fren u, u fren me.
Kid 2: (I) Dun fren u.
('dun' sounds like 'doe' with vowel nasalisation - derived from 'don't')
Or something like that - it's been a while since I was in kindergarten.
It conveys a sense of liking someone, something to the effect of 'I want to be friends with you, do you want to be friends with me?'. But adults may still jokingly say to one another, 'I dun/donch fren you' if the other person offends them mildly.
I then asked people if they preferred the verb 'unfriend' or 'defriend' (neither of which is in Singlish kid speak). The unanimous response at the table was 'unfriend', even though after some consideration, people realised that 'un-' generally negates adjectives while 'de-' negates verbs. One reason suggested for why 'unfriend' sounded better was the existence of the word 'unfriendly'.
Having done a bit of googling, I found this article:
The Un-believable Un-Verb from September 21, 2009, which explains that there is an 'un-' prefix added to verbs (marking the reversal of an action, e.g. 'unfasten', 'unmask' - and also 'undo') which has a different etymology to the 'un-' prefix added to adjectives. 'Unfriending' someone on Facebook therefore makes more sense since you are undoing the action of 'friending' them.
But I wonder if there are still people who would prefer 'defriend'?