From BiblePortal Wikipedia

Vine's Expository Dictionary of NT Words [1]

1: Ἐπιούσιος (Strong'S #1967 — Adjective — epiousios — ep-ee-oo'-see-os )

is found in  Matthew 6:11;  Luke 11:3 . Some would derive the word from epi, "upon," and eimi, "to be," as if to signify "(bread) present," i.e., sufficient bread, but this formation is questionable. The same objection applies to the conjecture, that it is derived from epi, and ousia, and signifies "(bread) for sustenance." The more probable derivation is from epi, and eimi, "to go," (bread) for going on, i.e., for the morrow and after, or (bread) coming (for us). See the RV marg. This suits the added semeron, "to-day," i.e., the prayer is to be for bread that suffices for this day and next, so that the mind may conform to Christ's warning against anxiety for the morrow. Confirmation of this derivation is also to be found in the word epiouse, in the phrase "the next day,"  Acts 7:26;  16:11 .

2: Ἐφήμερος (Strong'S #2184 — Adjective — ephemeros — ef-ay'-mer-os )

signifies "for the day" (epi, "upon, or for," hemera, "a day," Eng., "ephemeral"),  James 2:15 .

3: Καθημερινός (Strong'S #2522 — Adjective — kathemerinos — kath-ay-mer-ee-nos' )

means, lit., "according to" (kata) "the day" (hemera), "day by day, daily,"  Acts 6:1 .

 Luke 11:3 Acts 3:2 16:5 1—Corinthians 15:31 Hebrews 7:27 2—Corinthians 4:16 2—Peter 2:8 2—Corinthians 3:14,15 James 4:13 Romans 11:8  Luke 21:37 Acts 5:42 Acts 17:17 Hebrews 3:13

Webster's Dictionary [2]

(1): ( adv.) Every day; day by day; as, a thing happens daily.

(2): ( n.) A publication which appears regularly every day; as, the morning dailies.

(3): ( a.) Happening, or belonging to, each successive day; diurnal; as, daily labor; a daily bulletin.

King James Dictionary [3]

DA'ILY, a. Happening or being every day done day by day bestowed or enjoyed every day as daily labor a daily allowance.

Give us this day our daily bread. Lord's Prayer

DA'ILY, adv. Every day day by day as, a thing happen daily.

International Standard Bible Encyclopedia [4]

dā´li  : This word, coming as it does from the Hebrew יום , yōm "day," and the Greek ἡμέρα , hēméra , suggests either day by day ( Exodus 5:13 ), that which is prepared for one daily ( Nehemiah 5:18 ), as e.g. our "daily bread," meaning bread sufficient for that day ( Matthew 6:11 ); or day by day continuously, one day after another in succession, as "the daily burnt offering" ( Numbers 29:6 the King James Version), "daily ministration" (  Acts 6:1 ), and "daily in the temple" ( Acts 5:42 the King James Version). The meaning of the word "daily" as used in the Lord's Prayer (  Matthew 6:11 ) seems to indicate sufficient for our need, whether we consider that need as a day at a time, or day after day as we are permitted to live. "Give us bread sufficient for our sustenance."

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [5]

occurs in the Engl. version of our Lord's Prayer as the rendering of Ἐπιούσιος ( Matthew 6:11;  Luke 11:3), which literally means For Subsistence , i.e. Needful , as it probably should have been translated. The same Greek word occurs nowhere else, although several Hebrew and Greek words are thus translated in other passages. Conant, however (Revised Version of Matthew, N. Y. 1860, p. 30), maintains the correctness of the Auth. Vers., as does also Schaff (in Lange's Matthew, p. 121). But this involves a palpable tautology. (See Day). Treatises on the phrase "daily bread" have been written in Latin by Kirchmaier ( Viteb . 1711), Kortholt ( Kil . 1677), Stolberg ( Viteb . 1688), Pfeiffer ( Regiom . 1689), Zorn ( Opusc . 1:465-503). (See Lords Prayer).