It seems to belong to a 'family' of words that refer to places in Latin:
- ibi = there/in that place
- ubi = where/in what place?
- alibi = somewhere else/in some other place (or, pleasingly if archaically, otherwhere)
The weakened sense of "excuse" is attested since 1912, but technically any proof of innocence that doesn't involve being "elsewhere" is an excuse, not an alibi.
<digression theme="This is the way the world ends, not with a banger but with a wimpy"‡>
A similar weakening of a clear sense is happening to amnesty – the temporary suspension [or forgetting – think of 'mnemonic'] of a prohibition. This precise meaning works for 'gun amnesty', 'knife amnesty'... and so on - when people can hand in a weapon without admitting to illegal possession. But once a year, with a grating regularity that always seems to me to be quickening ('Time's wingéd chariot', I guess), Radio 5 Live participates in a Football Shirt Amnesty which when I first met it conjured up an image of shame-faced middle-aged men queuing up outside a Police Station to hand in a shirt: 'A friend wore it once, it wasn't me, honest... oh all right, it was me, but I was a lot younger then....'
My Latin Dictionary doesn't have a separate headword nullibi (well, it wouldn't have), but I assume it's the locative of nullus. So here's a fourth for my list of place-words:
- nullibi = in no place
But the hardcopy #WVGTbook calls. I should be getting proofs next week (or at least seeing them – I'm not sure of the actual nuts and bolts of the CreateSpace process).
†It reminds me of flocci-nauci-nihili-pilification, a nonce word with legs, coined from a schoolboy mnemonic about a common clutch of Latin prepositions.
‡With thanks to Frank Muir on My Word.
Update 2013.12.12.12:12 – Added this PS (actually at about a quarter past, but the timestamp was just too tempting)
PS Native speakers will know this already, because of anxiety, piety, satiety, sobriety, society, variety... and so on, but language students may not have this lexical background: it's /nʌlɪ'baɪǝti:/.
Update 2013.12.14.12:50 – Added purple passage.
Update 2013.12.15.16:00 – updated footer
Mammon When Vowels Get Together V5.2: Collection of Kindle word-lists grouping different pronunciations of vowel-pairs. Now complete (that is, it covers all vowel pairs – but there's still stuff to be done with it; an index, perhaps...?)
And if you have no objection to such promiscuity, Like this.
Freebies (Teaching resources: nearly 35,0300 views** and 5,000 downloads to date. They're very eclectic - mostly EFL and MFL, but one of the most popular is from KS4 History, dating from my PGCE, with 1796 views/838 downloads to date. So it's worth having a browse.)
** This figure includes the count of views for a single resource held in an account that I accidentally created many years ago.