Semi-

CIDE DICTIONARY

Semi-,  [L. semi; akin to Gr. , Skr. sāmi-, AS. sām-, and prob. to E. same, from the division into two parts of the same size. Cf. Hemi-, Sandelend.].

 A prefix signifying half, and sometimes partly or imperfectly; as, semiannual, half yearly; semitransparent, imperfectly transparent.  [1913 Webster]
" The prefix semi is joined to another word either with the hyphen or without it. In this book the hyphen is omitted except before a capital letter; as, semiacid, semiaquatic, semi-Arian, semiaxis, semicalcareous."  [1913 Webster]

OXFORD DICTIONARY

Semi-, prefix.
1 half (semicircle).
2 partly; in some degree or particular (semi-official; semi-detached).
3 almost (a semi-smile).
4 occurring or appearing twice in a specified period (semi-annual).

Etymology

F, It., etc. or L, corresp. to Gk HEMI-, Skr. sami

ROGET THESAURUS

Semi-

bisection

N bisection, bipartition, dichotomy, subdichotomy, halving, dimidiation, bifurcation, forking, branching, ramification, divarication, fork, prong, fold, half, moiety, bisected, cloven, cleft, bipartite, biconjugate, bicuspid, bifid, bifurcous, bifurcate, bifurcated, distichous, dichotomous, furcular, semi-, demi-, hemi.