4. The apparatus according to claim 1 , wherein the acquisition unit acquires the history information on the viewing of the word and the history information on usage of the word, and even if the history information on the viewing of the word does not meet a criterion that is related to the viewing of the word and predetermined as a criterion for presuming that the particular user knows the meaning of the word, the determination unit determines that the meaning of the word need not be presented to the particular user if the history information on the usage of the word meets a criterion that is related to the usage of the word and predetermined as a criterion for presuming that the particular user knows the meaning of the word.
4. The apparatus according to claim 1 , wherein the acquisition unit acquires the history information on the viewing of the word and the history information on usage of the word, and even if the history information on the viewing of the word does not meet a criterion that is related to the viewing of the word and predetermined as a criterion for presuming that the particular user knows the meaning of the word, the determination unit determines that the meaning of the word need not be presented to the particular user if the history information on the usage of the word meets a criterion that is related to the usage of the word and predetermined as a criterion for presuming that the particular user knows the meaning of the word. 5. The apparatus according to claim 4 , wherein the acquisition unit acquires the history information on the viewing of the word and the history information on the usage of the word, and if the history information on the viewing of the word does not meet a criterion that is related to the viewing of the word and predetermined as a criterion for presuming that the particular user knows the meaning of the word and if the history information on the usage of the word does not meet a criterion that is related to the usage of the word and predetermined as a criterion for presuming that the particular user knows the meaning of the word, the determination unit determines that the meaning of the word needs to be presented to the particular user.