Assalaamu alaykum. I am taking knowledge from a student of knowledge online. He said something that confused me, and now wonder whether he is reliable. He said that imaan (faith) is linked to the word ameen (used in 95:3), meaning secure. He said either (not sure which one) that this is one of the linguistic meanings of this word or that it is the root. However, I asked an Arab in person, and he said that there is no link and that he cannot see any way in which they would be linked. Is there any link in terms of the linguistic meaning, not the sharia meaning?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger. 

The word eemaan has two different usages. The Arabs use it to mean believing in (something) or granting safety.

As for its use to mean granting safety and security (amaan), it is said, "Aamantu so and so eemaana," or, "Ammantu so and so ta'meena," and they both have the same meaning: I gave security to so-and-so, or I kept so and so safe. Allaah, The Exalted, says (what means): {Who has fed them, (saving them) from hunger and made them safe from fear (Aamanahum min Khawf).} [Quran 106:4] He also says (what means): {He said: Should I entrust you (Aamanakum) with him except as I entrusted you (Amintukum) with his brother before?} [Quran 12:64]

The name  "Al-Mu'min" of Allaah is derived from "amn" or security/safety, because Allaah grants His servants security from fear and safety from punishment.

This usage of the word eemaan is manifest in the verse: {And by this secure city (Al-Balad Al-Ameen)} [Quran 95:3] Mukhtaar As-Sihaah reads, "Al-Akhfash said that Al-Ameen in this verse means the safe, secure city (Makkah), derived from amn (safety and security)." [Mukhtaar As-Sihaah, p.23]

The other usage of the word eemaan is to denote believing and admitting. The past tense verb "aamana" means he believed. Allaah, The Exalted, says (what means): {...But you would not believe us (mu'minin lana), even if we were truthful.} [Quran 12:17] He also says (what means): {Say: Make no excuse - never will we believe you (nu'mina lakum).} [Quran 9:94]

Ibn Al-ʻArabi wrote, "Eemaan may mean believing and it may mean security and safety (i.e. a synonym of amaan)..."

As for the relation between the two meanings of the word eemaan, the scholars held different views in this regard. Some argued that eemaan is derived from amn (security and safety), while others objected to this view and suggested that it is incorrect except in a figurative sense. Ibn Hajar wrote, "Eemaan is said to be derived from amn (safety/security), but this is debatable due to the variation between the meanings: security and belief, unless a metaphorical meaning is observed, like saying, 'Ammanahu' to mean 'he believed him,' i.e. regarded him as safe from lying." [Fat-h Al-Baari, 1/46]

Allaah knows best.