Q:

What is the adjective of the word "pity"?

Context:
I feel "pity" for all those poor people.
In dictionary it is written that it is noun.
So if want to convert or I want to say pity so that it looks as an adjective, then how would I do?

A:

There are three ways:

All those poor people are pitiful.
All those poor people are pitiable.
All those poor people are piteous.

The word pitiful can suggest that the speaker feels contempt toward all those poor people—that their poor state is their own fault, the result of low-quality work. Pitiable can also suggest contempt, but it's more likely to suggest compassion or resignation about the conditions that led to those people's poverty. Piteous indicates that all those poor people merit pity without implying anything about whether anyone actually feels pity toward them.
For more information, see this article in Merriam-Webster's Dictionary of Synonyms.
If you're wondering if there is a rule about whether -ful, -able, and -ous carry similar connotations when forming other adjectives: no, there isn't. English has a variety of ways to form adjectives, some from Anglo-Saxon (like -ful and -y) and some from Latin (like -able, -ous, -al). Adjectives formed by different endings often take on distinct meanings or connotations over the years. There are common patterns, which explain why the above connotations seem natural to a native ear, but they're hard to describe. If there's a rough rule of thumb, it's that words formed from Anglo-Saxon roots tend to be less formal or more suitable for pejorative meanings than comparable words from Latin roots (like bloody vs. sanguinous, or mouthy vs. oral), but it's not a rule.

