UNPLANNED
unintentional, unplanned, unwitting
(adjective) not done with purpose or intent; “an unintended slight”; “an unintentional pun”; “the offense was unintentional”; “an unwitting mistake may be overlooked”
unplanned
(adjective) without apparent forethought or prompting or planning; “an unplanned economy”; “accepts an unplanned order”; “an unplanned pregnancy”; “unplanned remarks”
Source: WordNet® 3.1
Etymology
Adjective
unplanned (comparative more unplanned, superlative most unplanned)
unintentional; not intended
spontaneous and not thought through in advance
not having any structure or organization
Synonyms
• (not intended): see also unintentional or accidental
• (not thought through in advance): see also impromptu
Antonyms
• planned
Source: Wiktionary