Penumbral

A penumbral lunar eclipse can be hard to see.

Source: tatoeba (5565241)

Relatedly, there are Fine's penumbral connections which reflect logical relations between indefinite sentences. He claims that, regarding a borderline red-pink blob, we are obliged to respect the truth of 'if the blob is to be red then it is not to be pink.'

Source: wiktionary

This would be the most far-reaching penumbral interpretation of the right to security, and might be called the "capabilities-based" interpretation. We have a right to security, in this view, because we have a right to live the "fully human" life such security in part ensures.

Source: wiktionary

The meaning of the term 'preventive or enforcement action' has prompted considerable discussion. Given the lack of practice under Art. 5, the depth and detail of this debate may be surprising. As will be shown, the core meaning of the term seems clear enough, and while there are some doubts about the penumbral meaning, the Organization's unwillingness or inability to apply Art. 5 means that this is unlikely to be particularly relevant.

Source: wiktionary