This study examines the language used by researchers in science and engineering, where clarity is essential. We prepared The Japanese-English Corpus of Presentations in Science and Engineering (JECPRESE) to examine how language is used in science and engineering to clearly and accurately present information. JECPRESE contains transcriptions of presentations given in Japanese and English by researchers. Analyses revealed vagueness in Japanese arising from the tendencies of the Japanese language to sometimes omit subjects and to lack specificity in conveying discourse strategies, verb tense, and mood. Such vagueness is considered to have roots in traditional Japanese society and culture that aim to maintain harmony in a community. However, in an age of global communications, this can be an obstacle to projecting an understandable message. Suggestions are made as to how to make scientific Japanese present clearer messages to a professional community based on linguistic considerations.