IPA: /ˈmiːnɪŋlɛsli/
KK: /ˈminɪŋlɪsli/
In a way that lacks meaning or purpose; without significance.
He spoke meaninglessly during the meeting, making it hard to follow his points.
Meaninglessly → It is formed from "meaning" (from Old English "mænan", meaning to signify or intend) and the suffix "-less" (meaning without). The word "meaninglessly" describes something that is without meaning or significance.
Think of something that is 'without' ('-less') 'significance' ('meaning') — that's why meaninglessly refers to something that lacks meaning.