Can mean the inability to describe emotions verbally.
Or, Sherlock, in the eyes of Mycroft Holmes.
In the eyes of Mycroft, Sherlock is weak.
He is weak for allowing his emotions to rule, as he does. To any normal, sane human being, Sherlock is frigid and emotionless. To those who spend time around him (indicating they are not, in fact, sane) he is loving, if not affectionate, and driven. Passionate.
As far as most people see it, Sherlock is a wasteland of emotion, barren land.
A cruel fact: Mycroft has been hurt more times than Sherlock. He held his mentor, the man who taught him how to play politics like a chess board, and that mentor's child, as their blank eyes stared upwards. He was stabbed in the back, literally, by his partner in the field (yes, did you think he got to where he is by not seeing the mechanisms of the dirty work?). He's seen his baby brother, high, separated from the world by a veil of 7% solution in his veins. Mycroft's felt the veil, too, but he stopped because he couldn't bear the feeling of being out of control in that manner.
As such he dislikes getting his hands dirty, and despises drugs, and abhors ruling emotions that render the bearer brittle and breakable.
To Mycroft, the 'Ice Man', who felt so much but lets nothing hurt, anymore, Sherlock is a upset balance of feeling.
In the eyes of Mycroft, Sherlock is impulsive.
This is yet another example of when the world sees Sherlock as the opposite of how Mycroft sees him.
To the world at large, Sherlock marks every move, and that's true. Every strike and twitch is a key stroke of a message. He sees so many plans, so many strategies, and so many agendas written on the faces and the clothes of those around him.
Another cruel fact: Sherlock is not a chess master. He is a puzzle solver. Mycroft is the chess player, who plays for the long game. Sherlock gets caught up in the puzzle, the intricate interlocking pieces of wood you have to twist just so. Sherlock never could win a chess match against Mycroft, which was something Mycroft never taunted him over because Mycroft didn't see that-in itself-as a bad thing.
It was a bad thing when Sherlock would throw away the figurative chess game for the sake of a puzzle.
In the eyes of Mycroft, Sherlock is vulnerable.
To Mycroft, Sherlock will always be a small toddler, learning to sound around words and take steps in the right direction, needing a little hand to hold to make it the next step.
To Mycroft, Sherlock will always be seen as sitting on the sofa, blissfully lost to the miracle that was the corruption of blood. Mycroft knew that feeling and cursed his brother for being weak enough to let it hold him, to fall into it yet again.
To Mycroft, Sherlock will always be beaten and bloodied and lost, away from the place he calls home. For a split second, he was vulnerable, and all the strength Sherlock wore between those weak moments couldn't eclipse those moments.
Mycroft leaned back in his chair and tapped his fingers, watching the CCTV cameras outside 221B, always protecting his brother.
Sherlock was a storm, a knifes-blade wind and bullets of hail. Mycroft was the underwater earthquake, the twisting of tectonic plates that starting a tsunami.
The two were very similar and very different, and Mycroft had no words to accurately portray that.
No words.