Radical (adjective / noun) — جذري أو مُتطرف في التغيير أو الآراء: Far-reaching and basic; favouring great change; a root in maths and chemistry. Below are 7 words with a similar meaning; the linked ones have full GL Dictionary entries with their meaning in Arabic.
Extreme in effect or action; severe or harsh; having a strong or far-reaching impact; characterized by radical change or measures
The part of a plant that grows underground; the origin or cause of something.
Developing gradually; also favouring social reform or new ideas.
fundamentalextremerevolutionarythorough
A person filled with extreme and uncritical enthusiasm, especially for a cause.
Combative and aggressive in support of a cause.
Seeking to undermine an established system or authority.
Wide in range or effect; made with a long, smooth movement.
Extreme; going beyond the usual limit.
Contrary to what is usual or accepted.