HW - heehaw
HX = helix
HY = hobbledehoy
HZ - Hertz
IA = iota
IM - intomb
IN - icon
Intomb should have been IB, with IC next.
IC = iconic
ID = indeed
IE - implode
IF = itself
IG - incorporating
IH - inch
II: Illuminati
IJ = ICOJ
acronym, International Court of Justice
Ik - ilk
IL - ill
IM (for real) idiom
IN = inspiration
IO: imbroglio