  In the last decades, multifunctional single-crystals that show, for example,
multiferroic and magnetoelectric responses have attracted considerable
attention due to the potential applications and physical phenomena involved in
the entanglement of the ferroic orders. This paper investigates the structural,
ferroelectric, and magnetic properties of the unexplored layered SrNiF$_4$
fluoride compound. We show that, in terms of the vibrational phonon modes, this
fluoride compound shows a tangible ferroelectric behavior with a spontaneous
polarization as large as $P_s$ = 14.8 $\mu$C$\cdot$cm$^{-2}$ standing as one of
the largest among its family. Besides, based on our findings such ferroelectric
polarization presents a geometric origin that is strongly entangled with the
octahedral rotations within the $\Gamma_2^-$ phonon mode and enhanced by the
structure's $\Gamma_1^+$ mode. We also observed that the spontaneous
polarization is coupled to the noncollinear $G$-type antiferromagnetic ordering
in the structure allowing a switching of the weak antiferromagnetic component
when the polarization is reversed.
