The term 'Igneous' is derived from the Latin word 'Ignis' which means:

The correct option is

Fire

Explanation

The scientific nomenclature of rock types is derived from Latin or Greek roots that describe their primary mode of formation.

Etymological Analysis:

• The term 'Igneous' is derived from the Latin word 'Ignis', which means Fire.
• This refers to the formation process of these rocks, which solidify from molten magma or lava. Due to the extreme heat associated with the molten state, the association with "fire" is used to classify them.

Comparison with other rock types:

• Sedimentary: Derived from the Latin word 'sedimentum', meaning settling (referring to the deposition of sediments).
• Metamorphic: Derived from the Greek word 'metamorphose', meaning change of form (referring to the alteration of existing rocks under heat and pressure).

Key Takeaway: Igneous rocks are primary rocks formed from the cooling of molten material, and their name strictly originates from the Latin 'Ignis', meaning Fire.