Sin-Mim-Ayn (س-م-ع) has 4 words in the Fahm dictionary: yasmaʿu (he hears / he listens), samīʿ (all-hearing), samiʿa (to hear / to listen), istamaʿa (to listen).
In the Quran, words built on this root occur 185 times in 163 verses, across 57 of the 114 suras. The first is in 2:7. The form سَمِعَ (to hear / to listen) accounts for 78 of them.
Have ye any hope that they will be true to you when a party of them used to listen to the word of Allah, then used to change it, after they had understood it, knowingly?
And when Abraham and Ishmael were raising the foundations of the House, (Abraham prayed): Our Lord! Accept from us (this duty). Lo! Thou, only Thou, art the Hearer, the Knower.
Quran 2:127
Arabic text: Tanzil Quran Text (Uthmani 1.1), CC BY 3.0, tanzil.net. English: Marmaduke Pickthall, The Meaning of the Glorious Koran (1930), public domain, via Project Gutenberg. Counts and verse choice: Quranic Arabic Corpus morphology data (corpus.quran.com).
Intensive adjective (فَعِيل pattern) from سَمِعَ (to hear). Often paired with بَصِيرٌ (all-seeing) or عَلِيمٌ (all-knowing).
Culture
As-Samīʿ (The All-Hearing) reassures believers that God hears every prayer, even silent ones. It also warns that no secret conversation escapes God's hearing.