Office action
An office action is the USPTO's official letter explaining why the application can't be approved as filed. It may contain requirements, such as clarifying the goods, adding a disclaimer, or submitting a better specimen, or refusals, the most common being likelihood of confusion and mere descriptiveness. The trap is the deadline: if neither a response nor an extension request is filed in time, the application is abandoned.
15 U.S.C. § 1062(b); 37 C.F.R. § 2.62; TMEP §§ 711, 718
Likelihood of confusion
The USPTO refuses a mark that is so similar to a registered or earlier-filed mark, for related goods or services, that buyers would likely think the two come from the same source. The marks need not be identical, and the goods need not be the same; they need only be related in the minds of consumers.
15 U.S.C. § 1052(d); TMEP § 1207.01
Merely descriptive
A mark that immediately tells buyers what the product is or does, such as CREAMY for yogurt, can't be registered on the Principal Register without proof that the public has come to see it as a brand. A suggestive mark, which hints at a quality and takes a moment's thought to connect, can be.
15 U.S.C. § 1052(e)(1), (f); TMEP § 1209.01
Disclaimer
A disclaimer is a statement that you claim no exclusive right in a descriptive word within your mark, apart from the mark as a whole, such as “BAKERY” in SUNRISE BAKERY. It doesn't remove the word from the mark or weaken the mark as a whole.
15 U.S.C. § 1056; TMEP § 1213