What makes a Gundam a Gundam

Depends on what series you are watching. In Gundam Wing, gundams are just mobile suits made of Gundanium (sp?). In Gundam Seed they were mobile suits with phase-shift armor (or something like that). In Gundam 00 only suits made by Celestial beings are called Gundams. Other series may vary.They also have 2 pointy things on the head.

Also, a Gundam in the UC is nothing more than a name.

• It is not a specific line of mobile suits.
• It is not a "type" of mobile suit even if it is referred to as "Gundam-Type Mobile Suit." All Gundams post the RX-78 series are named in a traditional fashion, not designed in accordance with.
• It is not a series of aesthetics such as V-fin as the Victory Gundam Hexa, and others, lack this feature but are still Gundams. The Hyaku Shiki was originally called the Delta Gundam but did not posess a V-fin or Gundam-style face.
  

don't make this question complicated man
gundams are just robots with "V" shaped aerials.