That's interesting, Brendan. Admittedly my eyesight isn't good, but here's the version on the web -
chambers co uk [add the dots]
Searching for a (or A) gives two entries for abbreviations -
A2 abbreviation 1 absolute (temperature). 2 cards ace. 3 acre or acres. 4 music alto. 5 ammeter. 6 ampere or amperes. 7 angstrom. 8 area. 9 argon. 10 atomic weight. 11 IVR Austria.
...
a2 abbreviation 1 acceleration. 2 acre or acres. 3 adjective. 4 are or ares. 5 area. 6 ante (Latin), before.
As the proud possessor of a 2G mobile, such things as 'apps' are beyond my ken. Perhaps the app has more extensive definitions than the web version?