If a proposed mark is not inherently distinctive, it may be registered on the Principal Register only upon proof of acquired distinctiveness, or “secondary meaning,” i.e., proof that it has become distinctive as applied to the applicant’s goods or services in commerce. If the applicant establishes, to the examining attorney’s satisfaction, that the matter in question has acquired distinctiveness as a mark in relation to the named goods or services, then the mark is registrable on the Principal Register under §2(f) of the Trademark Act [15 USC 1052(f)].
Secondary meaning arises when consumers have come to identify a trademark over time with a particular source of goods/services. An applicant’s proof of substantially exclusive & continuous use of a mark in commerce for 5 years before the claim of distinctiveness date, may be considered prima facie evidence that the mark has become distinctive.