The word "since" has several synonyms depending on its usage as a preposition, conjunction, or adverb.

Synonyms of "Since" as a Preposition (indicating time from a past point

to now):

• after
• from
• following
• subsequent to
• as of
• beyond
• starting from
• over
• during

Synonyms of "Since" as a Conjunction (indicating because or reason):

• because
• as
• given that
• considering that
• seeing that
• inasmuch as
• for

Synonyms of "Since" as an Adverb:

• ago
• previously
• before

These synonyms vary in strength of match and typical usage context but provide alternatives for expressing time or causation related to "since".