There are multiple definitions:

1. Institute for Scientific Information(English)

   • the forerunner of the Web of Science™
   • Biomedical journals, Medical publications, Organizations (documentation)
   • https://clariva…ic-information/

2. international sensitivity index(English)

   • standardizes the differences between prothrombin assays (PT) through a comparison with a WHO thromboplastin reagent
   • INR, PT, WHO, VKA
   • Hematology, Standards, Ratio-based metric
   • https://doi.org…16.21.1089.1089

3. interstimulus interval(English)

   • CS, TS
   • Electrophysiology
   • https://doi.org…nhum.2020.00202

4. interspike interval(English)

   • EPSP, FETi, ISF, STD
   • Electrophysiology
   • https://doi.org…598-018-31996-0

5. Indigenous Survival International(English)

   • Organizations (international)
   • https://www.un.…ts/DRIPS_en.pdf

6. International Statistical Institute(English)

   • WFS
   • Statistics, Organizations (international)
   • https://www.isi…b.org/index.php

7. insomnia severity index(English)

   • a brief instrument that was designed to assess the severity of both nighttime and daytime components of insomnia. This 7-item self-report questionnaire assesses the nature, severity, and impact of insomnia. The usual recall period is the “last month” and the dimensions evaluated are: severity of sleep onset, sleep maintenance, and early morning awakening problems, sleep dissatisfaction, interference of sleep difficulties with daytime functioning, noticeability of sleep problems by others, and distress caused by the sleep difficulties. A 5-point Likert scale is used to rate each item (e.g., 0 = no problem; 4 = very severe problem), yielding a total score ranging from 0 to 28. The total score is interpreted as follows: absence of insomnia (0–7); sub-threshold insomnia (8–14); moderate insomnia (15–21); and severe insomnia (22–28). Total scores are positively correlated with subjective sleep estimates and with PSQI total scores, indicating good convergent validity, at least with other patient-reported measures of sleep
   • IRT, PSQI
   • Sleep medicine, Screening, Epidemiology, Questionnaire, Scoring systems/scales
   • https://doi.org…/sleep/34.5.601

8. insulin sensitivity index(English)

   • for glucose metabolism (homeostasis model assessment and quantitative insulin sensitivity check index) and fat metabolism
   • SI
   • Insulin
   • https://doi.org….1002/dmrr.2292

9. inter-symbol-interference(English)

   • CIR, CSI, CSK, DFE, MAP
   • Communication, Nano-sciences
   • https://doi.org…NB.2015.2504542

10. influential scientific information(English)

    • COI, ERG, FDA, FOIA, HISI, IARC, ILCOR, MRTP, OMB, USEPA, WHO
    • Medical informatics, Medical publications, Decision making
    • https://doi.org…tph.2019.01.003

11. increased signal intensity(English)

    • severity is classified into three groups based on T2-weighted sagittal MRI: Grade 0, none; Grade 1, ISI limited to one disc level; or Grade 2, ISI beyond one disc level
    • BMI, MRI, OPLL
    • Spine (or spinal cord), Medical imaging, Classification, Gender aspects
    • https://doi.org…nee.2015.01.028