She takes more sick time than the other coworkers, it’s suspicious whether she’s really sick or not.
This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of suspicious? Also suspicious!
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: Our artist here at Tofugu/WaniKani/TextFugu is named Aya. She is very suspicious and shady looking.