IPA: /nɒnˈspɛktəˌkjʊlə/
KK: /nɑnˈspɛktəˌkjʊlər/
Not impressive or exciting; lacking in grandeur or showiness.
The movie was entertaining, but the ending was quite nonspectacular.
Nonspectacular → It is formed from "non-" (meaning not) and "spectacular" (from Latin "spectaculum", meaning a show or spectacle). The word "nonspectacular" means not having the qualities of a show or spectacle, or lacking in impressiveness.
Think of 'not' ('non-') and 'show' ('spectaculum') to remember that 'nonspectacular' means something that is not impressive or showy.