يقن1 يَقِنَهُ, (S, Msb, K,) and يَقِنَ بِهِ; (Msb;) and ↓ أَيْقَنَهُ, (S, K,) and بِهِ ↓ ايقن; (K;) and ↓ تَيَقَّنَهُ; and ↓ اِسْتَيْقَنَهُ, (S, Msb, K,) and ↓ استيقن بِهِ; (K;) all signify the same; (S;) He knew it; he was, or became, certain, or sure, or he made sure, of it; syn. عَلِمَهُ; (Msb, K;) intuitively, and inferentially; (Msb;) [see 1 in art. علم;] and تَحَقَقَّهُ. (K.) 4 أَيْقَنَ see 1.5 تَيَقَّنَ see 1.10 إِسْتَيْقَنَ see 1.يَقِينٌ is of the measure فَعِيلٌ in the sense of the measure فَاعِلٌ, signifying Sure, or certain, and manifest. (Msb.) b2:  And knowledge, or certainty; [see ظَنٌّ;] instinctive and inferential. (Msb.) b3:  عَيْنُ اليَقِينِ: see عَيْنٌ (latter part). b4:  الحقُّ اليَقِينُ and حَقُّ اليَقِينِ: see جَامِعٌ; where the two words are said to have the same meaning: and Bd and Jel in lvi. 95; in the latter of which, اليقين in حَقُّ اليَقِينِ is expressly said to be an epithet: see also Ham, p. 335.