adjective
red
A1
Rot means "red". It's an adjective describing color; gradable: comparative röter, superlative am rötesten. Antonym grün (green). Used attributively and predicatively; follows normal adjective declension in German depending on gender, case, and article. Not a participle. Often appears with noun agreement endings (rot, roter, rotes, rote).
Examples
Das Auto ist rot.
The car is red.
Das Auto, das gestern am Straßenrand stand, war rot, weil der Besitzer es erst kürzlich lackiert hatte.
The car that stood at the side of the road yesterday was red because the owner had only recently painted it.
Details
Mnemonics
Picture a bright red stop sign whenever you hear 'rot'.
Rot sounds like 'rot' in English (sounds same), imagine red.
Adjective — no gender, but when used with 'die' (die rote Blume) visualize feminine article with red flower.
Notes
Standard adjective; comparative is 'röter' and superlative 'am rötesten' (or 'rot — röter — am rötesten').