noun
Japanese-Spanish dictionary
Refers to a bilingual dictionary from Japanese to Spanish. The term is straightforward and commonly understood.
新しい日西辞典を買った。
I bought a new Japanese-Spanish dictionary.
西和辞典 is a Spanish-Japanese dictionary, while 日西辞典 is Japanese-Spanish.
Compound of 日 (にち, 'Japan/Japanese'), 西 (せい, 'Spain/Spanish'), and 辞典 (じてん, 'dictionary'). The reading にっせい is a contraction of にちせい.