kn-an initial combination common to all the Teutonic langs. and still retained by most. In English, the k is now silent, alike in educated speech and in most of the dialects; but it was pronounced app. till about middle of the 17th c. In the later 17th and early 18th c., writers on pronunciation give the value of the combination as =hn, tn, dn or simple n. The last was prob. quite established in Standard English by 1750. The k is still pronounced in some Scottish dialects; in others the guttural is assimilated to the dental, making tn-, esp. after vowels, as a tnife, my tnee.
kn-
Germanic consonant cluster; the sound is still evident in most sister languages but in English it has been reduced to "n-" in standard pronunciation since before 1750, and for about a century before that it had been pronounced hn-, dn-, tn-. It was fully voiced in Old and Middle English.