Correct spelling, explanation: the correct plural form of the noun calf, referring to a young bovine or human body parts, is calves. The reason for this is that calf follows the standard English rule for forming plurals of nouns ending in -f or -fe. In such cases, you typically change the -f or -fe to -ves to create the plural form. This is done to maintain pronunciation and avoid awkward combinations of sounds. So, calves is the correct form because it follows this rule. Calfs with an -s is not considered standard or correct in this context.

Definition of calves:
1. noun (plural), more than one young bovine animal, especially a domestic cow or bull in its first year
The farmer’s calves frolicked in the pasture, enjoying the warm sunshine.
She admired the adorable calves at the dairy farm, which would grow into healthy cows producing fresh milk.
2. noun (plural), the thick curved parts at the back of the human legs between the knees and the feet
After a strenuous workout, her calves were sore, and she decided to do some gentle stretches to alleviate the tension.
He noticed that his calves were well-defined and muscular, the result of months of dedicated weightlifting and cardio training.

Collocations with calves:
Some most commonly used collocations include:
1. Strong calves: refers to well-developed muscles in the lower part of the legs.
Regular jogging and cycling can help build strong calves.
2. Tight calves: describes a condition where the calf muscles feel tense or contracted.
Stretching exercises can relieve tight calves after a long run.
3. Newborn calves: describes young bovines that have recently been born.
The rancher took care of the newborn calves in the barn.
4. Sore calves: indicates calf muscles that are painful or achy, typically from overuse or strenuous activity.
He massaged his sore calves after completing a marathon.

Incorrect spelling, explanation: the reason you can’t spell calves as calfs is because calves follows the standard English rule for forming plurals of nouns ending in -f or -fe. In such cases, you typically change the -f or -fe to -ves to create the plural form. This is done to maintain pronunciation and avoid awkward combinations of sounds. Calves is the correct plural form because it follows this rule. Calfs with an -s would be considered incorrect in standard English when referring to more than one young bovine or human body parts.