Merge: Grounding/grounded

https://derpibooru.org/search?q=grounded  
https://derpibooru.org/search?q=grounding
 
I suggest making “grounding” the primary tag (edit: because some of these images are not past-tense grounding), but popularity-wise, grounded is the winner.

Should there be a distinction between “grounded” meaning flight is impossible/fobidden, and “grounded” meaning a disciplinary technique?