#Yes.

The OED describes "no-brainer" as the other answers say:

1. Something that requires or involves little mental effort or intelligence to perform or understand; esp. an easily made decision

But it also includes the definition you mention:

2. A foolish or unintelligent person or action.

They quote the sentence: "If a no-brainer wants to talk on the radio—even if the message makes no sense whatsoever—he or she can do it."

#But... It's worth noting that as a native English speaker, I wasn't familiar with this definition (and neither it seems, were the other answerers), so while it does exist, I would advise against using it unless you hear it often in your region.

Yes.

The OED describes "no-brainer" as the other answers say:

1. Something that requires or involves little mental effort or intelligence to perform or understand; esp. an easily made decision

But it also includes the definition you mention:

2. A foolish or unintelligent person or action.

They quote the sentence: "If a no-brainer wants to talk on the radio—even if the message makes no sense whatsoever—he or she can do it."

But...

It's worth noting that as a native English speaker, I wasn't familiar with this definition (and neither it seems, were the other answerers), so while it does exist, I would advise against using it unless you hear it often in your region.

#Yes.

The OED describes "no-brainer" as the other answers say:

1. Something that requires or involves little mental effort or intelligence to perform or understand; esp. an easily made decision

But it also includes the definition you mention:

2. A foolish or unintelligent person or action.

They quote the sentence: "If a no-brainer wants to talk on the radio—even if the message makes no sense whatsoever—he or she can do it."

It's worth noting that as a native English speaker, I wasn't familiar with this definition (and neither it seems, were the other answerers), so while it does exist, I would advise against using it unless you hear it often in your region.

#Yes.

The OED describes "no-brainer" as the other answers say:

1. Something that requires or involves little mental effort or intelligence to perform or understand; esp. an easily made decision

But it also includes the definition you mention:

2. A foolish or unintelligent person or action.

They quote the sentence: "If a no-brainer wants to talk on the radio—even if the message makes no sense whatsoever—he or she can do it."

#But... It's worth noting that as a native English speaker, I wasn't familiar with this definition (and neither it seems, were the other answerers), so while it does exist, I would advise against using it unless you hear it often in your region.