abbreviation of Latin manu scriptum (see manuscript); the plural is MSS, after the custom in Modern Latin.
1570s, "pertaining to Elysium (q.v.), the abode of the blessed after death." Hence, "exquisitely happy, full of the highest bliss."
early 15c., synnes, sinnes, a contraction of sithenes "since," from sithen (with adverbial genitive -es), from Old English siððan "afterward, from now on, hereafter, further, later, as soon as, after that," originally sið ðan "after that," from sið "after" (see sith) + ðan, weakened form of ðam, dative of ðæt (see that).
It was used from late 14c. as a conjunction, "from the time when, during the time after." As a preposition, "ever, from the time of," from 1510s; "from the time when," hence "as a consequence of the fact that." The modern spelling replaced syns, synnes 16c. to indicate a voiceless final -s- sound. The meaning "before now, ago," with some specifying word or phrase (long since, etc.) is from late 15c. Since when?, often expressing incredulity, is attested from 1907.
"having a definite purpose," 1871, formed after or from German tendenziös, from Tendenz "tendency," from Medieval Latin tendentia (see tendency).