IPA: /ˌɪnɪˈfɛktɪvli/
KK: /ɪnɪˈfɛktɪvli/
In a way that does not produce the desired result or effect.
The team worked ineffectively, leading to missed deadlines and poor outcomes.
Ineffectively → It is formed from "in-" (meaning not) and "effect" (from Latin "effectus", meaning result or outcome) and the suffix "-ively" (meaning in a manner). The word "ineffectively" means in a manner that does not produce a desired result or outcome.
Think of 'not' ('in-') producing a 'result' ('effect') — that's why doing something ineffectively means it doesn't achieve the desired outcome.