التشبيه: إلحاق أمرٍ بأمرٍ في وصفٍ بأداةٍ لغرضٍ.
Tashbih links one thing to another in a quality, by means of a comparison particle, for a purpose.
Linking two things means comparing them in a particular respect, not asserting that they are identical in every feature. The “quality” is the ground on which the resemblance is based.
A comparison particle is part of the basic formulation, even though an expressive simile may omit the particle or the named quality. The stated purpose may be to clarify, visualize or intensify an intended feature.