Explicit consent is required in the contract.
He explicitly rejected the proposal.
The noun form meaning 'explicit statement' or 'clear indication'; 明示的 is the adjectival form.
explicit interface
From 明示 (meiji, 'explicit statement') + 的 (-teki, '-like, -ive'). The base 明示 is composed of 明 (mei, 'clear, bright') and 示 (ji, 'show, indicate').