How to spell MODERNSIM correctly?

If you meant "modernism", a correct suggestion for the misspelling "modernsim" would be to add the missing 'm' at the end. Modernsim is not a recognized term, but modernism refers to the artistic and cultural movement that emerged in the late 19th century.

• modernism Modernism is an art movement that began in the early 20th century.
• moderns Moderns prefer minimalist design and clean lines over ornate and decorative styles.

Intertubing

• antedating
• entertain
• entertainer
• entertaining
• inditing
• inner-tubing
• intertwine
• interurban
• intuiting
• undertaking