ASTM D653-07f

Definitions in this standard are to be regarded as the correct ones for terms found in other ASTM standards of Committee D18. Certain terms may be found in more than one standard issued under the jurisdiction of this committee and many of these terms have been placed in this standard.

Terms that are defined in some textbooks may differ slightly from those in this standard. Definitions in Terminology D 653 are to be regarded as correct for ASTM usage

A number of the definitions include symbols and indicate the units of measurement. The symbols appear in italics immediately after the name of the term, followed by the unit in parentheses. No significance should be placed on the order in which the symbols are presented where two or more are given for an individual term. The applicable units are indicated by capital letters, as follows:
D—Dimensionless
F—Force, such as pound-force, ton-force, newton
L—Length, such as inch, foot, millimeter, and meter
M—Mass, such as kilogram, gram
T—Time, such as second, minute

Positive exponents designate multiples in the numerator. Negative exponents designate multiples in the denominator. Degrees of angle are indicated as “degrees.”

Expressing the units either in SI or the inch-pound system has been purposely omitted in order to leave the choice of the system and specific unit to the engineer and the particular application, for example:
FL⁻²—may be expressed in pounds-force per square inch, kilopascals, tons per square foot, etc.
LT⁻¹—may be expressed in feet per minute, meters per second, etc.

Where synonymous terms are cross-referenced, the definition is usually included with the earlier term alphabetically. Where this is not the case, the later term is the more significant.

Definitions marked with (ISRM) are included for the convenience of the user and were taken directly from the International Society for Rock Mechanics (see X1.3).

See Appendixes for References (X1) and Symbols (X2).