Hearing the news, he started to feel uneasy inside.
Tips
usage
The dí reading is bound to 嘀咕 (to mutter under one's breath, or to feel apprehensive) and 犯嘀咕 (to have misgivings). For the beep or drip sound, the reading is dī.
口 on the left is the indexing radical. It marks 嘀 as a sound, putting it alongside 嘟 honk and 嘛 modal particle. Whether a drip, a horn, or muttered speech, 口 signals noise through an opening.
啇 on the right supplies the sound, an exact match. It originally pictured the stem-base of a plant and now mostly serves as a phonetic. Same family: 滴 drop, 摘 to pluck, 敌 enemy.