| pop | arrive unexpectedly, move in suddenly |
| sudden | unexpected, unpredictable, unlooked for |
| surprise | take prisoner, capture [especially: suddenly, unexpectedly] |
| unawares | without warning, by surprise, unexpectedly |
| unawares | unexpectedly |
| unhoped | unexpected, unforeseen, unanticipated |
| unlooked | unexpected, unanticipated, unforeseen |
| unlooked-for | unexpected, unanticipated, unforeseen |
| unthought-on | unexpected, unforeseen, fortuitous |