ألا

From أَنْ‎ (ʾan) +‎ لَا‎ (lā).

أَلَّا • (ʾallā)

1. negate a verb if the following verb is in subjunctive

   ‏قَرَّرْتُ أَلَّا أَعْمَلَ فِيهِ‎

   qarrartu ʾallā ʾaʿmala fīhi

   I decided not to work in it.

2. lest, that [..] not, in order that [..] not, so as not to

أَلَا • (ʾalā)

1. verily, truly, indeed, oh yes!

From the root ء ل و‎ (ʾ-l-w).

أَلَا • (ʾalā) I, non-past يَأْلُو‎‎ (yaʾlū)

1. to neglect to do, to fail to do, not to do (with فِي‎ (fī))
2. to desist, to refrain (with فِي‎ (fī))
   • c. 1200, يحيى بن محمد بن أحمد بن العوام‎ [Yaḥyā ibn muḥammad ibn ʾaḥmad ibn al-ʿawwām], José Antonio Banqueri, editor, كتاب الفلاحة‎ [Book on Agriculture], volume 2, Madrid: Imprenta Real, published 1802^IA, Cap. 33, Art. 9, page 673:

     ‏فإذا أَرَدتَ فتح عرق أو وداج فخذ المبضع بين إصبعك الإبهام والسبّابة كأخذك القلم للكتابة به وليكن نصابه في راحتك وتخرج من رأسه خارج طرفي إصبعك المذكورين قدر طول ظفر إبهامك وأقلّ من ذلك إلى قدر نصف ظفر إبهامك ثم أفتح العرق إلى فوق شقّا بليغا برفق وخفّة. وأمّا التوديج يالقضيب وهو معلوم فتركب فيه المبضع وتخرج من طرفه خارج من القضيب قدر طول ظفر إبهامك، ولا تعجل بالضرب بالمبضع حتّى تقف على العرق بعينه وخاصة الوداجين، ولا تودّج حتّى تستوثق من الدابّة بالشكل والزيار ليألُ يضطرب وتختنق الدابّة بالخناق خنقا شديدا ليدرّ العرق. فإنّ ذلك موضوع خبيث وإن جاوزت يدك ربّما أصاب المبضع عرق الماء وهو المريء الدابّة فقتله.‎‎

     If you want to open a vein or jugular, take the scalpel between your thumb and index finger, take it like you take the quill for writing with it, so that its grip is in your palm, and you turn away from its head outwith the two tips of your said fingers by a length of the nail of your thumb and less than that by a half of the nail of your thumb, then you open the vein upwards making a sufficient cut with gentleness and levity. And what concerns the cutting the jugular with the known rod, you mount the scalpel in it and you move away from the rod’s tip by the length of the nail of your thumb, but don’t hasten with hitting with the scalpel until you have discerned the vein by its eye, particularly the two jugulars, and don’t do a jugular cut until you have provided for the security of the beast by hopples and a twitch, so you do not agitate or suffocate the beast at its throat by excessive choking, so the vein flows with abundance. This part being particularly perilous, if your hand go to far then the scalpel could hit the water vein [or windpipe], that is the oesophaghus of the beast, and it would kill it.

Morphologically from أَ‎ (ʾa) +‎ لَا‎ (lā).

أَلَا • (ʾalā)

1. do/does ... not, don't/doesn't (negative interrogative particle)

   ‏أَلَا تَعْرِفُ مَنْ هُوَ؟‎‎

   ʾalā taʿrifu man huwa?

   Do you not know who he is?

• Freytag, Georg (1830), “ألا”, in Lexicon arabico-latinum praesertim ex Djeuharii Firuzabadiique et aliorum Arabum operibus adhibitis Golii quoque et aliorum libris confectum (in Latin), volume 1, Halle: C. A. Schwetschke, pages 48–49, 52
• Lane, Edward William (1863), “ألا”, in Arabic-English Lexicon, London: Williams & Norgate, pages 75–77, 83–84
• Wehr, Hans (1979), “ألا”, in J. Milton Cowan, editor, A Dictionary of Modern Written Arabic, 4th edition, Ithaca, NY: Spoken Language Services, →ISBN, pages 27–28, 30