Converting Decimal to Words: Writing 0.5 in Word Form

To solve this problem, we need to express the decimal 0.5 as a fraction and then rewrite that fraction in words.

First, let's convert the decimal 0.5 into a fraction. The decimal 0.5 means that we have 5 parts out of 10, or $\frac{5}{10}$. In simplest terms, the decimal 0.5 is equivalent to the fraction where 5 is the numerator and 10 is the denominator.

Therefore, when expressed in words, 0.5 is "five divided by ten."
So, the correct answer choice is:

$\frac{5}{10}$