underlying

Important but not immediately clear, often explaining why something happens.

• We need to find the underlying problem.
• Stress may be an underlying cause of her headaches.
• His argument rests on an underlying assumption about human nature.

Common phrases: underlying cause, underlying problem, underlying assumption

Forming the basic ideas or structure that something depends on.

• The underlying idea is simple.
• We studied the underlying principles of the system.
• Both methods share the same underlying structure.

Similar words: basic, fundamental

Common phrases: underlying principle, underlying theory, underlying structure

Located below another thing or layer.

• The rain exposed the underlying rock.
• Remove the paint carefully to protect the underlying wood.
• The doctor checked for damage to the underlying tissue.

Similar words: lower

Opposites: overlying

Common phrases: underlying rock, underlying layer, underlying tissue