d.t.d. means dentur tales doses - give of such doses in Prescription
Similar to d.t.d.
a.u. - auris utraque - both ears aa - ana - of each ad - ad - up to ad lib. - ad libitum - use as much as one desires; freely admov. - admove - apply agit - agita - stir/shake alt. h. - alternis horis - every other hour