infinitesimal, presumptuous, dapper, rife, vigilant: meanings and examples

Learn these 5 words from SAT Vocabulary Level 3 set 132. Each entry includes a definition, example sentence, pronunciation, and synonyms. Use the interactive cards above to practice them.

1. infinitesimal · adjective/ˌɪn.fɪ.nəˈtɛs.ɪ.məl/

   an indefinitely small quantity that is smaller than any finite value

   The scientist measured an infinitesimal change in temperature that could influence the results of the experiment.

   Synonyms: tiny, minute, negligible

   Origin: Late Latin 'infinitesimus' meaning 'infinitely small'

2. presumptuous · adjective/prɪˈzʌmp.ʧu.əs/

   overstepping bounds of what is appropriate or permissible

   It was rather presumptuous of him to assume he could speak on behalf of the whole team without consulting anyone first.

   Synonyms: arrogant, overconfident, audacious

   Origin: from Middle French 'presomptueux' and Latin 'praesumptuosus', which means 'taking for granted'

3. dapper · adjective/ˈdæp.ɚ/

   neatly dressed and stylish in appearance

   He arrived at the wedding looking dapper in his tailored suit and polished shoes.

   Synonyms: stylish, smart, chic

   Origin: The word 'dapper' originates from the early 17th century, and it is thought to stem from the Middle Dutch word 'dapper,' meaning 'brave' or 'bold.'

4. rife · adjective/raɪf/

   existing or widespread in large numbers or quantities

   Corruption is rife in many levels of government, undermining public trust and accountability.

   Synonyms: common, prevalent, widespread

   Origin: Old English 'rifa', meaning 'abundant, plentiful'

5. vigilant · adjective/ˈvɪdʒɪlənt/

   keeping careful watch for possible danger or difficulties

   The neighborhood watch group remained vigilant in monitoring suspicious activities to keep residents safe.

   Synonyms: alert, watchful, attentive

   Origin: from Latin 'vigilans', present participle of 'vigilare', meaning 'to watch' or 'to be awake'