Floor panel for forming a floor covering, wherein this floor panel is rectangular, either oblong, or square, and thus comprises a first pair of opposite edges and a second pair of opposite edges; wherein both pairs of opposite edges (2-3, 4-5) comprise coupling parts (6-7, 8-9) which allow mutually coupling a plurality of such floor panels to each other; wherein these coupling parts (6-7, 8-9) on both pairs of edges (2-3, 4-5) form a first locking system, which, in a coupled condition of two of such floor panels, effects a locking in the plane of the floor panels and perpendicular to the respective edges, as well as form a second locking system, which, in a coupled condition of two of such floor panels, effects a locking transverse to the plane of the floor panels; wherein these coupling parts on the first pair of opposite edges substantially are realized in the material of the floor panel itself; wherein the coupling parts of at least the first pair of opposite edges are configured such that two of such panels can be coupled to each other at these edges by means of a turning movement and these coupling parts on the first pair of opposite edges to this aim consist of a tongue and a groove as well as of locking parts which, in the coupled condition, prevent the shifting apart of the tongue and groove; and wherein, on the first pair of opposite edges, the groove is bordered by a lower lip and an upper lip, of which the lower lip extends laterally to beyond the distal end of the upper lip; wherein on the first pair of edges the underside of the tongue comprises a step-shaped portion which, in the coupled condition of two of such panels, in respect to the groove side is situated mainly proximal from a vertical closing plane, wherein this vertical closing plane is defined as a vertical plane through the most distal end of the upper lip; characterized in that on the first pair of edges, the lower lip comprises a downward-directed recess, more particularly a depression, wherein this downward-directed recess, in the coupled condition of two of such panels, in respect to the groove side is situated mainly or entirely proximal from the vertical closing plane, wherein in coupled condition of two such floor panels at their first pair of opposite edges no contact is made between the recess and the bottom of the tongue; and wherein in the coupled condition of two of such panels, on said first pair of edges, a space is present underneath the tongue, which space extends from the tip of the tongue at least to beyond a vertical center plane through the zone over which the contact between the upper side of the tongue and the underside of the upper lip extends; that this space ends at a contact, herein after named first contact, formed by a contact point or a contact zone, between the underside of the tongue and the upper side of the lower lip; and that this contact, in distal direction of the groove, preferably ends and thus again merges into a space, wherein this transition, in respect to the groove side, is situated proximally to a theoretical vertical plane which, in respect to the groove side, is situated distally at a distance from the closing plane of the floor panel, which distance is smaller than 0.5 times the overall thickness and still better is smaller than 0.25 times the overall thickness; wherein the closing plane is defined as being a vertical plane through the most distal end of the upper lip. characterized in that on the first pair of edges, the lower lip comprises a downward-directed recess, more particularly a depression, wherein this downward-directed recess, in the coupled condition of two of such panels, in respect to the groove side is situated mainly or entirely proximal from the vertical closing plane, wherein in coupled condition of two such floor panels at their first pair of opposite edges no contact is made between the recess and the bottom of the tongue; and wherein in the coupled condition of two of such panels, on said first pair of edges, a space is present underneath the tongue, which space extends from the tip of the tongue at least to beyond a vertical center plane through the zone over which the contact between the upper side of the tongue and the underside of the upper lip extends; that this space ends at a contact, herein after named first contact, formed by a contact point or a contact zone, between the underside of the tongue and the upper side of the lower lip; and that this contact, in distal direction of the groove, preferably ends and thus again merges into a space, wherein this transition, in respect to the groove side, is situated proximally to a theoretical vertical plane which, in respect to the groove side, is situated distally at a distance from the closing plane of the floor panel, which distance is smaller than 0.5 times the overall thickness and still better is smaller than 0.25 times the overall thickness; wherein the closing plane is defined as being a vertical plane through the most distal end of the upper lip.