How to pronounce einsum

einsum is most commonly pronounced "ine sum" (/ˈaɪnsʌm/). This is the widely-used reading among engineers, though edge cases exist.

Clip of "Einstein summation" — the tensor-contraction primitive in NumPy/PyTorch/JAX (np.einsum, torch.einsum); NumPy docs confirm it "Evaluates the Einstein summation convention on the operands" (docs state the meaning, not the pronunciation). Stress on the first syllable: INE-sum, where "ein" rhymes with the start of Einstein /aɪn/ (like "wine"). Non-native devs commonly say "EEN-sum" (/iːn/) or "AYN-sum" (/eɪn/, as in "rein"); the German "ei" digraph is /aɪ/, not /iː/ or /eɪ/. Non-obvious because the clipped "ein-" hides its origin in the surname Einstein.

Source: NumPy docs — numpy.einsum (Einstein summation convention)

Pronouncing project and product names correctly avoids the small but persistent friction of being gently corrected during standups, conference Q&As, and team calls. Hearing the word a few times locks in the right reading better than reading IPA ever will. Pronounce is a community-maintained dictionary — every entry tagged with a confidence level and (where possible) a citable source.