definiens: . Antibody means ( a ) an antibody or antibody - related polypeptide including Fab, F(ab’)2, Fab ’, Fv, and single chain antibodies ( scFv ) containing a V[L ] and/or V[H ] domain joined by a peptide linker, where the scFv iscovalently or noncovalently linked to form antibodies having two or more binding sites ; or ( b ) other peptides which bind tothe Antibody Target ( as hereinafter defined in this Section 1.7 ) for example by having a binding domain ( protein ligand of thetarget, extracellular domain of a receptor, or a domain created by selection from random sequences such as by phage display)that may be genetically fused or chemically conjugated to a protein scaffold ( e.g., Adnectin ) or a stabilizing protein ( such asthe Fc domain of an antibody ) or to other macromolecules ( e.g., polyethelyene glycol ) for delivery purposes or to increase thevalency of the biological ; or ( c ) aptamers or other nucleic acid based polymers selected to bind tightly to the AntibodyTarget, said aptamers may be chemically modified to improve stability and/or may be coupled to other macromolecules toenhance in vivo delivery as in ( b ) above ; or ( d ) any other macromolecule having a molecular weight greater than 10,000daltons that behaves similarly to an antibody . For clarity, ( x ) molecules including siRNA which act inside the cell to modulategene expression of specified targets are not considered Antibodies for purposes of this Agreement, and ( y ) moleculesincluding an Antibody linked to a Non - Antibody Compound are not considered Antibodies for purposes of this Agreement, except where such Non - Antibody Compound is a radioisotope or toxin conjugate ( e.g., ricin or DM1 ) . As used in thisSection 1.7, means an extracellular drug target that can be inhibited or activated through the use of anappropriate that acts via direct binding to the or the ligand of such target . For purposes ofclarity, the use of in this definition in no way precludes Antibody Targets from being Candidate Targets, Nominated Targets or Collaboration Targets under this Agreement