NATO refers to airborne air defence as counter-air and naval air defence as anti-aircraft warfare. Missile defence is an extension of air defence as are initiatives to adapt air defence to the task of intercepting any projectile in flight.
TBH usually means To Be Honest, but it can also mean Honest Opinion. To Be Honest was the original meaning of TBH, but nowadays it often just means Honest Opinion or Honest Comment. Of note, TBH was originally used with a blunt or slightly antagonistic statement to suggest the statement derived from sincerity.
MCH stands for mean corpuscular hemoglobin. It refers to the quantity of hemoglobin in red corpuscles. To have your MCH blood test results explained you would need to visit the doctor. MCH is determined by the percentage of red cells and the amount of hemoglobin present in blood.