The largest circle inscribed in a rectangle will have a diameter equal to the smaller side of the rectangle. 
Here, the rectangle has sides 18 cm and 14 cm, so diameter \(d = 14\, \text{cm}\). 
Radius \(r = \frac{d}{2} = \frac{14}{2} = 7\, \text{cm}\). 
Area of circle \(= \pi r^2 = \pi \times 7^2 = 49\pi \approx 49 \times 3.14 = 153.86\, \text{cm}^2\). 
Hence, the area of the largest inscribed circle is approximately \(\boxed{154\, \text{cm}^2}\).