Common words:
* Reflect: To think deeply or carefully about something.
* Deflect: To turn aside or change the direction of something.
* Reflecting: The act of thinking deeply or carefully.
* Reflective: Thinking deeply or carefully; showing thought.
* Deflection: The act of turning something aside.
Less common words:
* Inflect: To change the pitch or tone of your voice.
* Inflection: A change in the pitch or tone of voice.
* Flex: To bend or move something.
* Flexible: Able to bend or move easily.
* Reflex: An automatic response to a stimulus.
* Reflexive: Done without thinking.
* Affliction: Something that causes pain or suffering.
* Conflicting: Disagreeing or being incompatible.
* Circumflect: To bend or curve something.
* Diffract: To spread out waves of light or sound.
* Reflector: A surface that reflects light or sound.
Words from other languages:
* Reflexive (French): "Reflexive"
* Reflective (German): "Reflektierend"
* Deflective (Spanish): "Deflectivo"
This list isn't exhaustive, but it gives you a good starting point!