Merriam Webster defines 'steadfast' as:
1 a: firmly fixed in place : immovable b: not subject to change
2: firm in belief, determination, or adherence : loyal
From the Online Etymology Dictionary we find a break down of the word 'steadfast' revealing another layer of significance:
O.E. stede "place, position, standing, delay," related to standan "to stand," from P.Gmc. *stadiz (cf. O.S. stedi, O.N. staðr, Swed. stad, Du. stede "place," O.H.G. stat, Ger. Stadt "town," Goth. staþs "place"), from PIE *stetis-, from base *ste-/*sta- "to stand" (see stet). Now chiefly in compounds or phrases. Steadfast is from O.E. stedefæst "secure in position," from stede + fæst "firmly fixed" (see fast).
O.E. fæst "firmly fixed, steadfast," probably from P.Gmc. *fastuz (cf. O.N. fastr, Du. vast, Ger. fest), from PIE base *past- "firm" (cf. Skt. pastyam "dwelling place"). The adv. meaning "quickly, swiftly" was perhaps in O.E., or from O.N. fast, either way developing from the sense of "firmly, strongly, vigorously" (cf. to run hard means to run fast; also compare fast asleep), or perhaps from the notion of a runner who "sticks" close to whatever he is chasing. The sense of "living an unrestrained life" (usually of women) is from 1746; fast food is first attested 1951. Fast-forward first recorded 1948. Fast and loose is described as "a cheating game played with a stick and a belt or string, so arranged that a spectator would think he could make the latter fast by placing a stick through its intricate folds, whereas the operator could detach it at once." [James O. Halliwell, "Dictionary of Archaic and Provincial Words," 1847]. The fig. sense (1557) is recorded earlier than the literal (1578).
After reading these definitions, the bells in my head are ringing like gongs!
Steadfast, remain steadfast...
After reading this, I went to BibleGateway.com to see where the word "steadfast" appears in scripture. I used the NIV translation and found 9 references of both the Old and New Testament. What stood out to me is the implication that steadfastness refers to or alludes to trusting God and remaining true to His Word.
Hmmmm....trust....trust. Remain steadfast in His Love, trust Him. God works all things together for good for those who love Him and are called according to His purpose...Remain in Me and I will remain in you...I know the plans I have for you, plans to prosper you not to harm you...Trust Me, remain steadfast in My Love, in Me.
Steadfastness: Remaining in Christ Jesus.