Explanation

The one-word substitution for a state, society, or group governed by old people is gerontocracy.

It refers to a political system where power is held by the elderly or senior members of society.

Explanation

The one-word substitution for the killing of one's son or daughter is filicide.

Filicide specifically refers to the act of a parent killing their own child.

Explanation

The one-word substitution for "relating to colors" is chromatic.

It refers to anything associated with or involving colors.

Explanation

A posthumous child is born after the death of the father.

The term "posthumous" specifically refers to events or persons occurring or born after a person's death.

Explanation

Soliloquy is defined as an act of speaking alone or to oneself.

It is a dramatic device where a character expresses their thoughts and feelings directly to the audience, often revealing inner emotions or reflections.

Explanation

A person who shows a great or excessive fondness for one's wife is "Uxorious."

It describes someone who is overly doting or submissive to their spouse.

Explanation

A group of followers hired to applaud at a performance is "Claque."

A claque is specifically a group paid to cheer or show enthusiasm.

Explanation

The phrase "that without which one cannot do" is a definition of the word "indispensable", which means essential, necessary, or crucial.

Something that is indispensable is absolutely necessary or required, and cannot be done without it.

Explanation

Nomadic is related to Itinerant.

As both terms describe a lifestyle characterized by constant movement or travel.

Nomadic people frequently move from place to place.

Itinerant refers to traveling or wandering from one location to another.

Explanation

Patriot is a person who loves his country.

Patriot means محب وطن