The meaning of Islam is a question of politics, theology, history, and their intersection in language. The most frequently repeated formulations today about the meaning of Islam, that “islām is related to salām” and that “Islam is peace,” reflect the way that Islam is constructed in language. Turning away from the study of the political language of Islam, this paper focuses on how Islam is constructed in political language. What does it mean to say that islām the word reflects something about Islam the religion? How does approaching Islam as either the subject or predicate of political action make possible? What philosophies of language are at play in avowals and dismissals of the linguistic fact that islām and salām are related? When and why do the meanings of the words islām and salām become windows into the “nature” of Islam? This paper is a study of the historicity of moments of definition-giving. First, it considers how politicians, journalists, academics, and civilians across the globe have repeated or rejected the statement, “Islam is peace.” it sketches the work that “Islam is peace” performs in light of anxieties about empire, secularism, and language. Second, it demonstrates that in seeking to define the word ‘islām,’ a strand of nineteenth-century European discourses opposed “Islam-islām is submission” to “Christianity is peace,” which also converged with contemporaneous racial discourses about the Smite. Thirdly, the paper turns to Islamic reformers and Islamists, to argue that when modernist Jamal al-Din al-Afghani writes “Islam is war,” and Islamist Hassan al-Banna writes “Islam is peace,” such instances are both reaction to and continuation of these European discourses. The paper thus turns to a comparison of the appearances of the words islām and salām in Quranic commentaries by Islamists to their appearances and definitions by numerous schools of classical tafsīr. I conclude by contrasting “Islam is p” to “God is p” for Hegel and for two tenth-century Islamic thinkers, and suggest some implications of these comparisons for secularism, Islamism, and the ideas of religion and peace.