How does adding -ous to change infect to infectious change the word,'s part of speech?

Answer 1

The word "infect" is a verb, which means to cause something to become contaminated or to transmit a disease. When you add the suffix "-ious" to form "infectious," the part of speech changes from a verb to an adjective. "Infectious" describes something that can cause infection, such as a disease or pathogen, which characterizes a noun. Thus, by adding "-ous," you transform the action of infecting into a descriptive quality related to infection.