One of the mysteries of the English language finally explained.
Synonyms of adventitious in English:
adventitious
See definition of adventitious
adjective
1‘he felt that the conversation was not entirely adventitious’
SYNONYMS
unplanned, unpremeditated, accidental, unintentional, unintended, unexpected, unforeseen, involuntary, chance, fortuitous, serendipitous, coincidental, casual, random, fluky, unlooked-for, unhoped-for, not bargained for, out of the blue, without warning
rare aleatory
ANTONYMS
planned
2‘some rural parishes recorded high adventitious populations’
SYNONYMS
foreign, alien, non-native, outside, external, extraneous, extrinsic
ANTONYMS
native, indigenous