The Cambridge Guide to Australian English Usage - Noel's ESL ...

polarity
“informal”. Webster’s English Usage has citations for them from the 1960s, and the
Oxford Dictionary from the 1970s.
The use of plus as a common noun is also established, as in a big plus. The
preferred plural in all dictionaries is with one s, although the Oxford has equal
numbers of citations for pluses and plusses. In Australian documents on the internet
(Google 2006), pluses is overwhelmingly preferred.
Note also the uses of plus as an adjective, in the plus factor and in a 20 kg plus
tuna or a lay trainer plus, where it has a special role as a postmodifier.
pm or p.m. This is the standard abbreviation for times of day which fall between
noon and midnight. It stands for Latin post meridiem “after midday”. Full stops
are not essential with it, since it cannot be confused with any other word, and its
time function is made clear by the numbers (between 1 and 12) which precede it.
However some writers and editors would use stops with it and its counterpart
am/a.m., in accordance with their general policy on lower case abbreviations (see
abbreviations section 2). In the Australian ACE corpus there were equal numbers
of pm and p.m.—18 instances of each. The stopless form pm is endorsed in the
Australian Government Style Manual (2002).
Note that pm times begin immediately after noon, and so the first minute after
12 noon (= 12 am) is 12.01 pm. This naturally means that 12 midnight is 12 pm,
and the first minute of the next day is 12.01 am. (It would be 00.01 in the 24-hour
clock.) By adding pm you indicate to readers that you’re not working with a 24-
hour clock. This may be important in making travel arrangements overseas where
24-hour schedules are much more widely used, and “Arriving at 6.30” would be
unhesitatingly interpreted as an early morning arrival. They would expect 18.30 (or
6.30 pm) if you meant the evening.
poetic or poetical See under -ic/-ical.
point For the use of this word in measuring typefaces, see under pica.
pokie, poky or pokey This informal word for a poker machine usually
appears in the plural, as in playing the pokies, which makes the spelling of the
singular a real question. Australian authorities all give preference to pokie, which
helps distinguish it from the adjective poky meaning “cramped”. (See further under
-ie/-y.) The spelling pokie also sets it apart from pokey, which is slang for “jail” in
North America.
polarity Language, like a magnetic field, may be charged either positively or
negatively. This polarity is rarely an issue in statements about the way things are,
because the facts of the situation decide whether it should be positive or negative.
Either:
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