Inconsiderate (adjective)

1. Not considerate or not thoughtful towards others.
2. Not showing concern or not showing consideration.

Origin:

This word is derived from the latin word "inconsideratus" which is formed by the combination of the prefix "in-" meaning "not" and the word "consideratus" meaning "thoughtful" or "considerate".

Examples:

1. He was inconsiderate and didn't think about how his actions would affect others.
2. She was inconsiderate and didn't return the book to the library on time.
3. The company was inconsiderate and didn't take the environment into consideration.
4. He was inconsiderate and didn't offer his seat to the elderly lady.
5. She was inconsiderate and didn't tell her friends she was running late.