S

Semen: the thick white fluid containing spermatozoa that is ejaculated by the male genital tract

Sequencing: Determination of the order of nucleotides (base sequences) in a DNA or RNA molecule or the order of amino acids in a protein

Sex chromosomes: Chromosomes that are different in the two sexes and involved in sex determination

Swab: a small piece of soft material used for cleaning a cut or for taking a small amount of substance from a body, or the substance itself which can then be tested