ht. is only a written short form of height — how tall a person or thing is. You see it on forms, clothing labels, furniture lists, and older measurement notes: ht. 170 cm. People almost never say “ht” out loud; they say “height”. The little dot marks it as an abbreviation. Though actually, some tables drop the dot (ht) or use Ht, and that still means height. It is not a spoken word and not a company name.

高度（書面縮寫）