1. (v.t.)ascertain to find out definitely; learn with certainty or assurance.
2. ascertain Archaic. to make certain, clear, or definitely known.
Etymology: (1400–50; < MF acertain-,acertener to make certain)
Definition of 'ascertain'
Princeton's WordNet
1. (verb)determine, find, find out, ascertain establish after a calculation, investigation, experiment, survey, or study "find the product of two numbers"; "The physicist who found the elusive particle won the Nobel Prize"
2. (verb)see, check, insure, see to it, ensure, control, ascertain, assure be careful or certain to do something; make certain of something "He verified that the valves were closed"; "See that the curtains are closed"; "control the quality of the product"
3. (verb)determine, check, find out, see, ascertain, watch, learn find out, learn, or determine with certainty, usually by making an inquiry or other effort "I want to see whether she speaks French"; "See whether it works"; "find out if he speaks Russian"; "Check whether the train leaves on time"
4. (verb)ascertain learn or discover with certainty
Definition of 'ascertain'
Webster Dictionary
1. (verb)ascertain to render (a person) certain; to cause to feel certain; to make confident; to assure; to apprise
2. (verb)ascertain to make (a thing) certain to the mind; to free from obscurity, doubt, or change; to make sure of; to fix; to determine
3. (verb)ascertain to find out or learn for a certainty, by trial, examination, or experiment; to get to know; as, to ascertain the weight of a commodity, or the purity of a metal
Definitions of ascertain 
Afrikaans: sekermaak, uitvind
Arabic: يَتَحَقَّق، يَتَأكَّد مِن
Bulgarian: установявам
Brazilian: descobrir
Czech: zjistit
German: feststellen
Danish: finde ud af
Greek: εξακριβώνω, διαπιστώνω
Spanish: esclarecer, descubrir
Estonian: kindlaks tegema
Farsi: اثبات کردن؛ معلوم کردن
Finnish: varmistua
French: établir
Hebrew: לְבַרֵר
Hindi: पता लगाना
Croatian: utvrditi
Hungarian: kiderít
Indonesian: menemukan, memastikan
Icelandic: gangaúr skugga um
Italian: accertare
Japanese: 確かめる
Korean: 규명하다
Lithuanian: sužinoti, iš(si)aiškinti,
Latvian: noskaidrot; izdibināt
Malay: memastikan
Dutch: vaststellen
Norwegian: finne ut, bringe på det r
Polish: poznawać, ustalać
Persian: اثبات کردن؛ معلوم کردن
Pashto: معلومول، ثابت کول
Portuguese: descobrir
Romanian: a afla
Russian: устанавливать
Slovak: zistiť
Slovenian: ugotoviti
Serbian: ustanoviti
Swedish: utröna
Thai: สืบให้แน่ใจ
Turkish: ortayaçıkarmak, doğrusunu
Taiwanese: 查明
Ukrainian: встановлювати; з'ясовуват
Urdu: تحقیق کرنا ، پتہ چلانا
Vietnamese: tìm ra
Chinese: 查明
