IPA: /ˌɪnkənˈsɪdəˌrɛtli/
KK: /ˌɪnkənˈsɪdərətli/
In a way that shows a lack of thought for the feelings or needs of others.
He spoke inconsiderately, not caring how his words affected her feelings.
Inconsiderately → It is formed from "in-" (meaning not), "considerare" (meaning to consider), and "-ly" (meaning in a manner). The word describes acting in a manner that does not take others into account or is thoughtless.
Think of 'not considering' ('in-') others when you act — that's what inconsiderately means.