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• sis
  sis

  noun

  sister.
• -sis
  -sis

  a suffix appearing in loanwords from Greek, where it was used to form from verbs abstract nouns of action, process, state, condition, etc..
• SIS
  SIS

  abbreviation

  (in Britain) Secret Intelligence Service

sis

¹ American  

[sis] / sɪs /

noun

Informal.

1. sister.

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-sis ² American  

1. a suffix appearing in loanwords from Greek, where it was used to form from verbs abstract nouns of action, process, state, condition, etc..

   thesis; aphesis.

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SIS ¹ British  

abbreviation

1. Also called: MI6.  (in Britain) Secret Intelligence Service

2. (in New Zealand) Security Intelligence Service

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sis ² British  

/ sɪs /

noun

1. informal short for sister

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sis ³ British  

/ siːs, sɪs /

interjection

1. informal an exclamation of disgust

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Etymology

Origin of sis¹

1825–35, shortened form; compare Dutch zus for zuster sister

Origin of -sis²

From Greek

Example Sentences

Sallay was promoted to head the SIS, Sri Lanka’s main intelligence agency, following Rajapaksa's victory, but was dismissed after Anura Kumara Dissanayake won the presidency in 2024, promising prosecutions of those behind the attacks.

From Barron's • Feb. 25, 2026

Slovakia's domestic intelligence service, the SIS, has confirmed the claims, but has given few details.

From BBC • Jan. 24, 2025

SIS Chief Richard Moore disclosed in July 2022 that China’s intelligence services are “extraordinarily well-resourced,” the report said.

From Washington Times • Jul. 19, 2023

Yim also credits writing groups like SIS Writers Group and Theatre Battery for helping her development over the years.

From Seattle Times • Apr. 14, 2022

As head of the SIS and Yardley’s effective successor, William was closely watched.

From "The Woman All Spies Fear" by Amy Butler Greenfield

Related Words

• buddy
• comrade
• crony
• playmate