Correct spelling, explanation: most of us consider stylus as a rather modern word while in fact the word already appeared in Latin, but it referred to a part of a flower pistil. Stylus was also influenced by a Greek form stylos. When it comes to English, stylus appeared at the beginning of the 19th century and it referred to an instrument for writing.

Definition of stylus:
1. noun – a pointed part of a record player, which picks up the sound signals stored on a vinyl record,
For better sound quality of music, you need to keep the stylus clean.
2. noun – a pointed, plastic, or metal stick, which you use to write on some electronic device,
My work has improved since I started to use a stylus while using my tablet.

Phrases with stylus:
A few common phrases with stylus include: electronic stylus, light stylus, and stylus pen.
An electronic stylus is really useful when you’re giving a presentation as you can highlight what you want in a simple way.
He showed me a light stylus, which can be used as an alternative to a computer mouse.
If you want to do some mathematical calculations on this tablet, I recommend using a stylus pen.

Incorrect spelling, explanation: stylus doesn’t sound English and maybe because of that it causes some spelling problems. A number of English users associate stylus with another English word, which is still, and probably because of that one of the most common spelling mistakes is to write stylus as stilus, which is incorrect.