* -ly: This suffix is used to form adverbs, indicating manner or direction. For example, straightly means in a straight manner.
* -ness: This suffix is used to form nouns that describe a quality or state. For example, straightness refers to the quality of being straight.
* -form: This suffix can be used to describe a shape or form. For example, straight-form could be used to describe something that has a straight shape.
* -line: This suffix can be used to describe something that has a straight line. For example, straightline could be used to describe a straight line itself.
The specific suffix you choose will depend on the specific meaning and context of the word you are trying to create.