Mind-boggling (adjective)

1. Intellectually or emotionally overwhelming or confusing.
2. Extremely complex or difficult to understand or comprehend.

Origin:

From 'mind' meaning 'intellect' or 'consciousness' and 'boggle' meaning 'to confuse or perplex'.

Examples:

1. The mathematical problem was mind-boggling.
2. The mind-boggling complexity of the machine was a challenge to comprehend.
3. The mind-boggling beauty of the landscape was breathtaking.
4. The mind-boggling speed of the race car was awe-inspiring.
5. The mind-boggling array of options was overwhelming.