Sometimes there are different forms of the same adjective. If one joke makes a person laugh more than another joke, then that joke is funnier. This is called the comparative form. The day that is colder than any other is the coldest day. This is the superlative form of "cold". Some adjectives need additional words when we want to compare them. For instance, one car may be cheaper than another, but the second car may be more reliable (we use "more reliable", instead of "reliabler"). Reliable means worthy of trust.