Fertile

adj.hopeful, capableprofessional

Meaning 1

Able to sustain abundant biological growth.

Reach for it when describing soil, land, or an organism's capacity to produce new life

The river leaves a strip of fertile ground along the lower field.

everyday
rich
soil contains abundant nutrients
not when Rich is vague unless the agricultural context is already clear.
professional
productive
the land's output is the measured concern
not when Productive can reflect machinery and labor rather than natural fertility.
formal
arable
land is suitable for growing crops
not when Arable land may be usable without being especially fertile.
literary
fruitful
abundant yield deserves a positive, slightly figurative tone
not when Fruitful often describes results rather than the land's capacity.

Rich in possibilities that can develop into ideas or results.

Reach for it when describing an imagination, discussion, or situation that generates useful possibilities

The unresolved question became fertile ground for three new experiments.

warm
inventive
original solutions come from a person's creativity
not when Inventive describes the creator, not the conditions that encourage ideas.
professional
generative
an exchange actively produces new ideas or work
not when Generative sounds technical when praising a person's imagination in a card.
professional
prolific
a person or source produces a large volume
not when Volume alone does not mean the ideas are useful or promising.
literary
suggestive
one idea opens several further interpretations
not when Suggestive can carry ambiguity or innuendo that fertile need not.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.