Usually, trademarks are refused because of their descriptive character or lack of distinctiveness or because of the similarity in sound, appearance or meaning when compared to already registered trademarks.
The distinctiveness of a trademark means that the sign serves to identify the product and/or services in respect of which registration is applied for as originating from a particular undertaking, and thus to distinguish that product from those of other undertakings. The distinctiveness can be assessed only by reference first to the goods or services in respect of which registration is sought. That is why, a word “Apple” is distinctive for such goods as computers, but it would not be distinctive, for such goods as fruits.
A sign must be refused as descriptive if it has a meaning which is immediately perceived by the relevant public as providing information about the goods and services applied for. This is the case where the sign provides information about, among other things, the quantity, quality, characteristics, purpose, kind and/or size of the goods or services. The relationship between the term and the goods and services must be sufficiently direct and specific. In the European Union, a trademark is descriptive if it is descriptive in any of the official languages of the European Union, regardless of the size or population of the respective country.
As regards similarity with the earlier marks, it is sufficient if those marks are quite similar and the goods or services are related. In such a case the presumption is that consumers would mistakenly believe the goods came from the same source, what would definitely cause a conflict in the future. However, in multiple jurisdictions, trademark offices do not check these similarities and leave it for applicants to do the job. Instead, the officials would examine the trademarks in the light of absolute grounds for refusal, i.e. originality, distinctiveness, whether they can form a trademark etc.