In Australia a merely descriptive trademark is one that has no “adaptation to distinguish” your goods and services from those of other businesses. Some examples of such “merely descriptive” trademarks include words which are used for the normal description of the goods or services.

An example of this is the word “GIANT” in relation to hamburgers, which was held to be a word that was merely descriptive as it was likely to be used by other restaurants in the description of their hamburgers.

You can get more details about descriptive marks here.