This International Standard specifiesthe fundamental terms and definitions applicable to screw threads, in English and French. These terms are applicable to symmetrical threads and unsymmetrical threads, or cylindrical threads and taper threads. If more than one term applies to a definition, the term in bold letters should be given preference. Several terms, for which the definitionsare not included in the text, are given in Annex A. NOTE In addition to terms used in English and French,two of the three official ISO languages, this documentgives the equivalent terms in German, Chinese,Japanese and Swedish (see Annex B); these are published under the responsibility of the member bodies for Germany (DIN), China (SAC), Japan (JISC) and Sweden (SIS) and are given for information only. Only the terms given in the two official languages can be considered as ISO terms.