bilateral symmetry 
noun [mass noun]
The property of being divisible into symmetrical halves on either side of a unique plane.With few exceptions, animal color patterns show a high degree of bilateral symmetry in shape of pattern elements....
- Ours, however, is closed along the plane of bilateral symmetry, resembling the two closed valves of a bivalve rather than being flattened.
- Exhibiting external bilateral symmetry about a vertical midline, the human body consists of two enantiomorphs - the right and left sides.
- strand
- stranded
- strandlooper
- strandloper
- strandwolf
- strange
- strange attractor
- strange-looking
- strangely
- strangeness
- strange particle
- stranger
- stranger danger
- strange to say (or literary tell)
- strangle
- stranglehold
- strangler
- strangles
- strangulate
- strangulation
- strangurious
- strangury
- Stranraer
- strap
- strap-hang