1 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 إِِسْتَيْقَنَ 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. Credit: Lane Lexicon