The word 地老天荒 is formed by combining two parallel subject-predicate phrases: 地老, where 地 (earth) is the subject and 老 (grows old) is the predicate, and 天荒, where 天 (heaven) is the subject and 荒 (becomes desolate) is the predicate. The two phrases are juxtaposed to create a hyperbolic compound meaning, illustrating an extreme duration through the literal imagery of the earth aging and the heavens turning barren.