front line vs frontal

front line

noun
  • A front, or a boundary between opposing positions. 

  • A low level. 

  • attack, collectively the attackers or forwards. 

  • A site of a conflict, effort, or controversial matter of any kind. 

  • The site of interaction with outsiders, such as customers. 

frontal

noun
  • The façade of a building. 

  • A decorative drapery covering the front of an altar. 

adj
  • Of or relating to a weather front. 

  • Parallel to the main axis of the body and at right angles to the sagittal plane. 

  • Any of the scales of a reptile that lie in the general region of the forehead, more specifically between the eyes and to the anterior of this area. 

  • Of, relating to, directed toward, or situated at the front. 

  • Directed against the front or at the main point or issue. 

  • Of or relating to the forehead or frontal bone. 

How often have the words front line and frontal occurred in a corpus of books? (source: Google Ngram Viewer )