A teaching site offers this rule for dealing with “silent k”: “k is often silent before n.”
An easier way to retain this information is to forget about “silent k” altogether. In a word like knot, k is not “a silent letter” at all, but part of the distinct phonogram kn.
The symbol kn is just another way to spell the sound /n/.
The spelling kn in a word like knave evolved from the Old English spelling cn, in which the “c” represented a guttural sound similar to the sound /k/. For example, the OE words from which our words knight, knot, and knave have evolved were spelled cniht, cnotta, and cnafa and pronounced with a hard first sound. The guttural sound eventually dropped out, leaving only the /n/ sound, but the old spelling has survived in kn.
Here are some familiar kn words.
Here are some more kn words that may not be as familiar:
knacker (noun): One whose trade it is to buy worn out, diseased, or useless horses, and slaughter them for their hides and hoofs, and for making dog’s-meat. Ex. “Jones will sell you to the knacker, who will cut your throat and boil you down for the foxhounds.” (Animal Farm, George Orwell)
knackered (adjective): exhausted. “After shopping with Mum, we were knackered.”
knickerbockers (noun): loose-fitting breeches, gathered in at the knee, and worn by boys, sportsmen, and others who require a freer use of their limbs. Ex. “The child…was dressed in knickerbockers, with red stockings.” (Daisy Miller, Henry James)
knickers (noun): underpants worn by women and children. The word is a back-formation of knickerbockers. It’s commonly heard in the idiom, “to get one’s knickers in a twist” (i.e., “become upset”).
knackwurst (noun): a type of German sausage. Also spelled knockwurst.
knout (noun): a kind of whip or scourge, very severe and often fatal in its effects. Ex. “The knout along with the gulag are Russia’s enduring shrines of torment.”
knurl (noun): a small protuberance, excrescence, or knob.
knurled (adjective): having knurls wrought on the edge or surface.
Knurling is a process of impressing a diamond-shaped or straight-line pattern into the surface of a work piece by using specially shaped hardened metal wheels. Ex.
“Walnut Knurled Guitar Knob.” “Solid walnut knurled legs on table and chairs.”
Two foreign borrowings, Knesset and knish, do not belong to the category of words spelled with the phonogram kn. They are spelled with the phonogram k; the sound /k/ is pronounced at the beginning of these words.
Knesset (noun): The parliament of the State of Israel. The word derives from a Hebrew word meaning “a gathering.” Ex. “On July 11, 1995 this problem was raised for discussion in the Knesset finance committee.”
knish (noun): A dumpling of flaky dough filled with chopped liver, potato, or cheese, and baked or fried. The word comes from a Yiddish word derived from a Russian word meaning “a kind of cake.” Ex. “Gabila’s Knishes: Home of the Coney Island Square Knish.”