IPA: /ˌɪn.sɪɡˈnɪf.ɪ.kənt.li/
KK: /ɪnˌsɪɡnɪfɪkəntli/
In a way that is too small or unimportant to be noticed or considered significant.
The changes in temperature were insignificantly small, barely affecting the overall results.
Insignificantly → It is formed from "in-" (meaning not), "significare" (meaning to signify or indicate), and "-ly" (meaning in a manner). The word means in a manner that does not signify or indicate importance.
Think of 'not' ('in-') signifying anything important ('significare') — that's why insignificantly means something that does not matter.