with
  t_what(what) as
    (
      select 'ГородРегионПоселок'   from dual union all
      select 'КрайОбласть Район'    from dual union all
      select 'Хутор Село'           from dual
    ),
  t_dict(full_name, short_name) as
    (
      select 'Город'    , 'Гор' from dual union all
      select 'Регион'   , 'Рег' from dual union all
      select 'Поселок'  , 'Пос' from dual union all
      select 'Край'     , 'К'   from dual union all
      select 'Область'  , 'Обл' from dual union all
      select 'Район'    , 'Рай' from dual union all
      select 'Село'     , 'С'   from dual
    )
select rn, old_what, rtrim(new_what) as new_what
from t_what
model
reference t_d on (select t.*, rownum rn from t_dict t)
dimension by (rn) measures (full_name, short_name)
main t_w dimension by (rownum rn) measures (what old_what, what new_what)
rules iterate (999)
(new_what[any] = replace(new_what[cv()], full_name[iteration_number], short_name[iteration_number] || ' ')
);

        RN OLD_WHAT           NEW_WHAT
---------- ------------------ ------------------
         1 ГородРегионПоселок Гор Рег Пос
         2 КрайОбласть Район  К Обл  Рай
         3 Хутор Село         Хутор С

with
  t_what(what) as
    (
      select 'ГородРегионПоселок'   from dual union all
      select 'КрайОбласть Район'    from dual union all
      select 'Хутор Село'           from dual
    ),
  t_dict(full_name, short_name) as
    (
      select 'Город'    , 'Гор' from dual union all
      select 'Регион'   , 'Рег' from dual union all
      select 'Поселок'  , 'Пос' from dual union all
      select 'Край'     , 'К'   from dual union all
      select 'Область'  , 'Обл' from dual union all
      select 'Район'    , 'Рай' from dual union all
      select 'Село'     , 'С'   from dual
    )
select rn, old_what, rtrim(new_what) as new_what
from t_what
model
reference t_d on (select t.*, rownum rn from t_dict t)
dimension by (rn) 
measures (full_name, short_name) unique single reference
main t_w 
dimension by (rownum rn) 
measures (what old_what, what new_what) unique single reference
rules iterate (999999999) until presentv(full_name[iteration_number + 1], 1, 0) = 0
(new_what[any] =  replace(new_what[cv()], full_name[iteration_number + 1], short_name[iteration_number + 1] || ' ')
);