0th or zeroth may refer to:
Mathematics, science and technology 0th or zeroth, an ordinal for the number 0 0th dimension, a topological space 0th element, of a mathematical sequence or some data structure in computer science 0th law of Thermodynamics Zeroth (software), deep learning software for mobile devices
Other uses 0th grade, another name for kindergarten January 0 or , an alternate name for December 31 0 Avenue, a road in British Columbia straddling the Canada-US border
See also OTH (disambiguation) (with a letter O) Zeroth law (disambiguation) Zeroth-order (disambiguation)