The term "philosopher of the frontier" when related to Gundisalvo, commonly refers to the role and contributions of Dominicus Gundisalvo, also known as Domingo Gundisalvo, who was a significant medieval translator and philosopher.

Significance:

1. Cultural Bridge: Gundisalvo is often seen as a "philosopher of the frontier" because he played a pivotal role in the transmission of knowledge between the Islamic world and the Latin-speaking Christian West. This was during a time when medieval Spain, particularly the region of Toledo, was a critical boundary — or "frontier" — between these two cultures.

2. Translation Movement: Gundisalvo was heavily involved in the translation of Arabic philosophical and scientific texts into Latin. He worked in Toledo during the 12th century, a time when the city was burgeoning as a center for intellectual exchange due to the coexistence of Christian, Muslim, and Jewish communities.

3. Philosophical Contributions: He translated significant works of Islamic philosophers who were influenced by ancient Greek philosophers. This included notable figures such as Avicenna (Ibn Sina) and Al-Farabi. Through his translations, Gundisalvo helped incorporate Aristotelian and Neoplatonic thought into the Scholasticism that would dominate medieval European philosophy.

4. Intellectual Frontier: As a "frontier" philosopher, Gundisalvo represents a period of cultural syncretism where boundaries of religious and philosophical doctrine were transcended through intellectual inquiry, laying groundwork for the European Renaissance.

5. Legacy: His work exemplifies the importance of cross-cultural interactions and the movement of ideas across borders, which has contributed to shaping Western philosophy and science.

For further reading, you might look into sources that explore the history of medieval philosophy or the translation movement in Toledo, such as those found in academic articles and historical texts. Gundisalvo’s efforts highlight the essential role of mediators in the history of philosophy, facilitating the exchange of knowledge between disparate cultures.