People use idiomatic phrases—such as “hold down the fort”—frequently in speech, but less often in writing. Because of this they are often written with an incorrect homonym—words that sound alike but are spelled differently. Mark Nichol, writing at Daily Writing Tips, offers a list of common spelling mistakes in idioms.
“Eke out a living.” “Eke” is commonly misspelled as “eek.” To “eke out a living” means to work hard to achieve enough to survive, while “eek” is a sound made when you’re startled.
To “make do.” This means to get by with available resources. “Due,” which is sometimes used incorrectly in this phrase, means something is planned for at a specific time.
“Martial law.” This is sometimes incorrectly written as “marshal law.” While a marshal is a law enforcement official, the phrase refers to military forces taking control under warlike conditions.
“Pique your interest.” “Pique” means to stimulate or rouse. This phrase is sometimes erroneously written as “peak your interest.”
“Sleight of hand.” Magicians are known to use sleight of hand, with “sleight” meaning dexterity to deceive. The incorrect version is “slight of hand.”
“Toe the line.” Frequently misspelled as “tow the line,” this phrase means you put your feet right at the line without stepping over it.
“Whet your appetite.” This is misspelled as “wet your appetite,” as in to moisten it. “Whet” means to sharpen something—like your appetite.
“Rein in.” To “rein in” refers to controlling something, as in the use of reins on a horse. The mistake comes when people spell it “reign,” which refers to holding a position of royalty.
“Sow doubt.” “Sow” is used here in the sense of planting seeds. You “sow doubt” in someone’s mind by planting tidbits of information to make them doubt something. It’s often confused with “sew,” which refers to stitching fabric together.
— Adapted from “12 Idioms Commonly Seen with Homonymic Spelling Errors,” Mark Nichol, Daily Writing Tips.